514 lines
19 KiB
JavaScript
514 lines
19 KiB
JavaScript
/*! LAB.js (LABjs :: Loading And Blocking JavaScript)
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v2.0.3 (c) Kyle Simpson
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MIT License
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*/
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(function(global){
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var _$LAB = global.$LAB,
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// constants for the valid keys of the options object
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_UseLocalXHR = "UseLocalXHR",
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_AlwaysPreserveOrder = "AlwaysPreserveOrder",
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_AllowDuplicates = "AllowDuplicates",
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_CacheBust = "CacheBust",
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/*!START_DEBUG*/_Debug = "Debug",/*!END_DEBUG*/
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_BasePath = "BasePath",
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// stateless variables used across all $LAB instances
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root_page = /^[^?#]*\//.exec(location.href)[0],
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root_domain = /^\w+\:\/\/\/?[^\/]+/.exec(root_page)[0],
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append_to = document.head || document.getElementsByTagName("head"),
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// inferences... ick, but still necessary
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opera_or_gecko = (global.opera && Object.prototype.toString.call(global.opera) == "[object Opera]") || ("MozAppearance" in document.documentElement.style),
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/*!START_DEBUG*/
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// console.log() and console.error() wrappers
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log_msg = function(){},
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log_error = log_msg,
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/*!END_DEBUG*/
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// feature sniffs (yay!)
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test_script_elem = document.createElement("script"),
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explicit_preloading = typeof test_script_elem.preload == "boolean", // http://wiki.whatwg.org/wiki/Script_Execution_Control#Proposal_1_.28Nicholas_Zakas.29
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real_preloading = explicit_preloading || (test_script_elem.readyState && test_script_elem.readyState == "uninitialized"), // will a script preload with `src` set before DOM append?
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script_ordered_async = !real_preloading && test_script_elem.async === true, // http://wiki.whatwg.org/wiki/Dynamic_Script_Execution_Order
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// XHR preloading (same-domain) and cache-preloading (remote-domain) are the fallbacks (for some browsers)
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xhr_or_cache_preloading = !real_preloading && !script_ordered_async && !opera_or_gecko
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;
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/*!START_DEBUG*/
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// define console wrapper functions if applicable
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if (global.console && global.console.log) {
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if (!global.console.error) global.console.error = global.console.log;
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log_msg = function(msg) { global.console.log(msg); };
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log_error = function(msg,err) { global.console.error(msg,err); };
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}
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/*!END_DEBUG*/
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// test for function
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function is_func(func) { return Object.prototype.toString.call(func) == "[object Function]"; }
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// test for array
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function is_array(arr) { return Object.prototype.toString.call(arr) == "[object Array]"; }
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// make script URL absolute/canonical
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function canonical_uri(src,base_path) {
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var absolute_regex = /^\w+\:\/\//;
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// is `src` is protocol-relative (begins with // or ///), prepend protocol
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if (/^\/\/\/?/.test(src)) {
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src = location.protocol + src;
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}
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// is `src` page-relative? (not an absolute URL, and not a domain-relative path, beginning with /)
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else if (!absolute_regex.test(src) && src.charAt(0) != "/") {
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// prepend `base_path`, if any
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src = (base_path || "") + src;
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}
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// make sure to return `src` as absolute
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return absolute_regex.test(src) ? src : ((src.charAt(0) == "/" ? root_domain : root_page) + src);
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}
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// merge `source` into `target`
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function merge_objs(source,target) {
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for (var k in source) { if (source.hasOwnProperty(k)) {
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target[k] = source[k]; // TODO: does this need to be recursive for our purposes?
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}}
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return target;
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}
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// does the chain group have any ready-to-execute scripts?
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function check_chain_group_scripts_ready(chain_group) {
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var any_scripts_ready = false;
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for (var i=0; i<chain_group.scripts.length; i++) {
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if (chain_group.scripts[i].ready && chain_group.scripts[i].exec_trigger) {
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any_scripts_ready = true;
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chain_group.scripts[i].exec_trigger();
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chain_group.scripts[i].exec_trigger = null;
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}
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}
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return any_scripts_ready;
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}
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// creates a script load listener
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function create_script_load_listener(elem,registry_item,flag,onload) {
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elem.onload = elem.onreadystatechange = function() {
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if ((elem.readyState && elem.readyState != "complete" && elem.readyState != "loaded") || registry_item[flag]) return;
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elem.onload = elem.onreadystatechange = null;
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onload();
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};
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}
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// script executed handler
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function script_executed(registry_item) {
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registry_item.ready = registry_item.finished = true;
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for (var i=0; i<registry_item.finished_listeners.length; i++) {
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registry_item.finished_listeners[i]();
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}
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registry_item.ready_listeners = [];
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registry_item.finished_listeners = [];
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}
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// make the request for a scriptha
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function request_script(chain_opts,script_obj,registry_item,onload,preload_this_script) {
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// setTimeout() "yielding" prevents some weird race/crash conditions in older browsers
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setTimeout(function(){
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var script, src = script_obj.real_src, xhr;
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// don't proceed until `append_to` is ready to append to
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if ("item" in append_to) { // check if `append_to` ref is still a live node list
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if (!append_to[0]) { // `append_to` node not yet ready
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// try again in a little bit -- note: will re-call the anonymous function in the outer setTimeout, not the parent `request_script()`
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setTimeout(arguments.callee,25);
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return;
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}
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// reassign from live node list ref to pure node ref -- avoids nasty IE bug where changes to DOM invalidate live node lists
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append_to = append_to[0];
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}
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script = document.createElement("script");
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if (script_obj.type) script.type = script_obj.type;
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if (script_obj.charset) script.charset = script_obj.charset;
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// should preloading be used for this script?
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if (preload_this_script) {
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// real script preloading?
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if (real_preloading) {
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/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("start script preload: "+src);/*!END_DEBUG*/
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registry_item.elem = script;
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if (explicit_preloading) { // explicit preloading (aka, Zakas' proposal)
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script.preload = true;
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script.onpreload = onload;
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}
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else {
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script.onreadystatechange = function(){
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if (script.readyState == "loaded") onload();
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};
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}
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script.src = src;
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// NOTE: no append to DOM yet, appending will happen when ready to execute
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}
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// same-domain and XHR allowed? use XHR preloading
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else if (preload_this_script && src.indexOf(root_domain) == 0 && chain_opts[_UseLocalXHR]) {
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xhr = new XMLHttpRequest(); // note: IE never uses XHR (it supports true preloading), so no more need for ActiveXObject fallback for IE <= 7
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/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("start script preload (xhr): "+src);/*!END_DEBUG*/
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xhr.onreadystatechange = function() {
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if (xhr.readyState == 4) {
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xhr.onreadystatechange = function(){}; // fix a memory leak in IE
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registry_item.text = xhr.responseText + "\n//@ sourceURL=" + src; // http://blog.getfirebug.com/2009/08/11/give-your-eval-a-name-with-sourceurl/
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onload();
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}
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};
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xhr.open("GET",src);
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xhr.send();
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}
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// as a last resort, use cache-preloading
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else {
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/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("start script preload (cache): "+src);/*!END_DEBUG*/
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script.type = "text/cache-script";
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create_script_load_listener(script,registry_item,"ready",function() {
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append_to.removeChild(script);
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onload();
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});
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script.src = src;
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append_to.insertBefore(script,append_to.firstChild);
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}
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}
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// use async=false for ordered async? parallel-load-serial-execute http://wiki.whatwg.org/wiki/Dynamic_Script_Execution_Order
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else if (script_ordered_async) {
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/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("start script load (ordered async): "+src);/*!END_DEBUG*/
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script.async = false;
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create_script_load_listener(script,registry_item,"finished",onload);
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script.src = src;
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append_to.insertBefore(script,append_to.firstChild);
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}
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// otherwise, just a normal script element
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else {
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/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("start script load: "+src);/*!END_DEBUG*/
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create_script_load_listener(script,registry_item,"finished",onload);
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script.src = src;
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append_to.insertBefore(script,append_to.firstChild);
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}
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},0);
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}
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// create a clean instance of $LAB
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function create_sandbox() {
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var global_defaults = {},
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can_use_preloading = real_preloading || xhr_or_cache_preloading,
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queue = [],
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registry = {},
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instanceAPI
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;
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// global defaults
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global_defaults[_UseLocalXHR] = true;
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global_defaults[_AlwaysPreserveOrder] = false;
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global_defaults[_AllowDuplicates] = false;
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global_defaults[_CacheBust] = false;
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/*!START_DEBUG*/global_defaults[_Debug] = false;/*!END_DEBUG*/
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global_defaults[_BasePath] = "";
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// execute a script that has been preloaded already
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function execute_preloaded_script(chain_opts,script_obj,registry_item) {
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var script;
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function preload_execute_finished() {
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if (script != null) { // make sure this only ever fires once
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script = null;
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script_executed(registry_item);
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}
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}
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if (registry[script_obj.src].finished) return;
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if (!chain_opts[_AllowDuplicates]) registry[script_obj.src].finished = true;
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script = registry_item.elem || document.createElement("script");
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if (script_obj.type) script.type = script_obj.type;
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if (script_obj.charset) script.charset = script_obj.charset;
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create_script_load_listener(script,registry_item,"finished",preload_execute_finished);
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// script elem was real-preloaded
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if (registry_item.elem) {
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registry_item.elem = null;
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}
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// script was XHR preloaded
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else if (registry_item.text) {
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script.onload = script.onreadystatechange = null; // script injection doesn't fire these events
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script.text = registry_item.text;
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}
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// script was cache-preloaded
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else {
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script.src = script_obj.real_src;
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}
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append_to.insertBefore(script,append_to.firstChild);
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// manually fire execution callback for injected scripts, since events don't fire
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if (registry_item.text) {
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preload_execute_finished();
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}
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}
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// process the script request setup
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function do_script(chain_opts,script_obj,chain_group,preload_this_script) {
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var registry_item,
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registry_items,
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ready_cb = function(){ script_obj.ready_cb(script_obj,function(){ execute_preloaded_script(chain_opts,script_obj,registry_item); }); },
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finished_cb = function(){ script_obj.finished_cb(script_obj,chain_group); }
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;
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script_obj.src = canonical_uri(script_obj.src,chain_opts[_BasePath]);
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script_obj.real_src = script_obj.src +
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// append cache-bust param to URL?
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(chain_opts[_CacheBust] ? ((/\?.*$/.test(script_obj.src) ? "&_" : "?_") + ~~(Math.random()*1E9) + "=") : "")
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;
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if (!registry[script_obj.src]) registry[script_obj.src] = {items:[],finished:false};
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registry_items = registry[script_obj.src].items;
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// allowing duplicates, or is this the first recorded load of this script?
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if (chain_opts[_AllowDuplicates] || registry_items.length == 0) {
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registry_item = registry_items[registry_items.length] = {
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ready:false,
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finished:false,
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ready_listeners:[ready_cb],
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finished_listeners:[finished_cb]
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};
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request_script(chain_opts,script_obj,registry_item,
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// which callback type to pass?
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(
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(preload_this_script) ? // depends on script-preloading
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function(){
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registry_item.ready = true;
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for (var i=0; i<registry_item.ready_listeners.length; i++) {
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registry_item.ready_listeners[i]();
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}
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registry_item.ready_listeners = [];
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} :
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function(){ script_executed(registry_item); }
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),
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// signal if script-preloading should be used or not
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preload_this_script
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);
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}
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else {
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registry_item = registry_items[0];
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if (registry_item.finished) {
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finished_cb();
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}
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else {
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registry_item.finished_listeners.push(finished_cb);
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}
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}
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}
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// creates a closure for each separate chain spawned from this $LAB instance, to keep state cleanly separated between chains
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function create_chain() {
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var chainedAPI,
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chain_opts = merge_objs(global_defaults,{}),
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chain = [],
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exec_cursor = 0,
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scripts_currently_loading = false,
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group
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;
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// called when a script has finished preloading
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function chain_script_ready(script_obj,exec_trigger) {
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/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("script preload finished: "+script_obj.real_src);/*!END_DEBUG*/
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script_obj.ready = true;
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script_obj.exec_trigger = exec_trigger;
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advance_exec_cursor(); // will only check for 'ready' scripts to be executed
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}
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// called when a script has finished executing
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function chain_script_executed(script_obj,chain_group) {
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/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("script execution finished: "+script_obj.real_src);/*!END_DEBUG*/
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script_obj.ready = script_obj.finished = true;
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script_obj.exec_trigger = null;
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// check if chain group is all finished
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for (var i=0; i<chain_group.scripts.length; i++) {
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if (!chain_group.scripts[i].finished) return;
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}
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// chain_group is all finished if we get this far
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chain_group.finished = true;
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advance_exec_cursor();
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}
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// main driver for executing each part of the chain
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function advance_exec_cursor() {
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while (exec_cursor < chain.length) {
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if (is_func(chain[exec_cursor])) {
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/*!START_DEBUG*/if (chain_opts[_Debug]) log_msg("$LAB.wait() executing: "+chain[exec_cursor]);/*!END_DEBUG*/
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try { chain[exec_cursor++](); } catch (err) {
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/*!START_DEBUG*/if (chain_opts[_Debug]) log_error("$LAB.wait() error caught: ",err);/*!END_DEBUG*/
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}
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continue;
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}
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else if (!chain[exec_cursor].finished) {
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if (check_chain_group_scripts_ready(chain[exec_cursor])) continue;
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break;
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}
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exec_cursor++;
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}
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// we've reached the end of the chain (so far)
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if (exec_cursor == chain.length) {
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scripts_currently_loading = false;
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group = false;
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}
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}
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// setup next chain script group
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function init_script_chain_group() {
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if (!group || !group.scripts) {
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chain.push(group = {scripts:[],finished:true});
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}
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}
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// API for $LAB chains
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chainedAPI = {
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// start loading one or more scripts
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script:function(){
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for (var i=0; i<arguments.length; i++) {
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(function(script_obj,script_list){
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var splice_args;
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if (!is_array(script_obj)) {
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script_list = [script_obj];
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}
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for (var j=0; j<script_list.length; j++) {
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init_script_chain_group();
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script_obj = script_list[j];
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if (is_func(script_obj)) script_obj = script_obj();
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if (!script_obj) continue;
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if (is_array(script_obj)) {
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// set up an array of arguments to pass to splice()
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splice_args = [].slice.call(script_obj); // first include the actual array elements we want to splice in
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splice_args.unshift(j,1); // next, put the `index` and `howMany` parameters onto the beginning of the splice-arguments array
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[].splice.apply(script_list,splice_args); // use the splice-arguments array as arguments for splice()
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j--; // adjust `j` to account for the loop's subsequent `j++`, so that the next loop iteration uses the same `j` index value
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continue;
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}
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if (typeof script_obj == "string") script_obj = {src:script_obj};
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script_obj = merge_objs(script_obj,{
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ready:false,
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ready_cb:chain_script_ready,
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finished:false,
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finished_cb:chain_script_executed
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});
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group.finished = false;
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group.scripts.push(script_obj);
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do_script(chain_opts,script_obj,group,(can_use_preloading && scripts_currently_loading));
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scripts_currently_loading = true;
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if (chain_opts[_AlwaysPreserveOrder]) chainedAPI.wait();
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}
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})(arguments[i],arguments[i]);
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}
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return chainedAPI;
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},
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// force LABjs to pause in execution at this point in the chain, until the execution thus far finishes, before proceeding
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wait:function(){
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if (arguments.length > 0) {
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for (var i=0; i<arguments.length; i++) {
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chain.push(arguments[i]);
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}
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group = chain[chain.length-1];
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}
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else group = false;
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advance_exec_cursor();
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return chainedAPI;
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}
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};
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// the first chain link API (includes `setOptions` only this first time)
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return {
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script:chainedAPI.script,
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wait:chainedAPI.wait,
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setOptions:function(opts){
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merge_objs(opts,chain_opts);
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return chainedAPI;
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}
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};
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}
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// API for each initial $LAB instance (before chaining starts)
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instanceAPI = {
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// main API functions
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setGlobalDefaults:function(opts){
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merge_objs(opts,global_defaults);
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return instanceAPI;
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},
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setOptions:function(){
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return create_chain().setOptions.apply(null,arguments);
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},
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script:function(){
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return create_chain().script.apply(null,arguments);
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},
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wait:function(){
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return create_chain().wait.apply(null,arguments);
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},
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// built-in queuing for $LAB `script()` and `wait()` calls
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// useful for building up a chain programmatically across various script locations, and simulating
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// execution of the chain
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queueScript:function(){
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queue[queue.length] = {type:"script", args:[].slice.call(arguments)};
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return instanceAPI;
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},
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queueWait:function(){
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queue[queue.length] = {type:"wait", args:[].slice.call(arguments)};
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return instanceAPI;
|
|
},
|
|
runQueue:function(){
|
|
var $L = instanceAPI, len=queue.length, i=len, val;
|
|
for (;--i>=0;) {
|
|
val = queue.shift();
|
|
$L = $L[val.type].apply(null,val.args);
|
|
}
|
|
return $L;
|
|
},
|
|
|
|
// rollback `[global].$LAB` to what it was before this file was loaded, the return this current instance of $LAB
|
|
noConflict:function(){
|
|
global.$LAB = _$LAB;
|
|
return instanceAPI;
|
|
},
|
|
|
|
// create another clean instance of $LAB
|
|
sandbox:function(){
|
|
return create_sandbox();
|
|
}
|
|
};
|
|
|
|
return instanceAPI;
|
|
}
|
|
|
|
// create the main instance of $LAB
|
|
global.$LAB = create_sandbox();
|
|
|
|
|
|
/* The following "hack" was suggested by Andrea Giammarchi and adapted from: http://webreflection.blogspot.com/2009/11/195-chars-to-help-lazy-loading.html
|
|
NOTE: this hack only operates in FF and then only in versions where document.readyState is not present (FF < 3.6?).
|
|
|
|
The hack essentially "patches" the **page** that LABjs is loaded onto so that it has a proper conforming document.readyState, so that if a script which does
|
|
proper and safe dom-ready detection is loaded onto a page, after dom-ready has passed, it will still be able to detect this state, by inspecting the now hacked
|
|
document.readyState property. The loaded script in question can then immediately trigger any queued code executions that were waiting for the DOM to be ready.
|
|
For instance, jQuery 1.4+ has been patched to take advantage of document.readyState, which is enabled by this hack. But 1.3.2 and before are **not** safe or
|
|
fixed by this hack, and should therefore **not** be lazy-loaded by script loader tools such as LABjs.
|
|
*/
|
|
(function(addEvent,domLoaded,handler){
|
|
if (document.readyState == null && document[addEvent]){
|
|
document.readyState = "loading";
|
|
document[addEvent](domLoaded,handler = function(){
|
|
document.removeEventListener(domLoaded,handler,false);
|
|
document.readyState = "complete";
|
|
},false);
|
|
}
|
|
})("addEventListener","DOMContentLoaded");
|
|
|
|
})(this); |