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Execute a callback once required scripts have been loaded.
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| //require(scriptList, onSuccess[, onFailure]) | |
| //usage: | |
| //require(["a.js", "b.js"], function (){ /*scripts have loaded; do stuff*/ }, function (){ /*one or more scripts didn't load; handle error*/ }); | |
| // | |
| //scriptList can just be a string if there's only one script | |
| var require = (function (){ | |
| var head = document.getElementsByTagName("head")[0]; | |
| function require(scriptList, onSuccess, onFailure){ | |
| "use strict"; | |
| var i, len, url, pending = []; | |
| scriptList = [].concat(scriptList); | |
| len = scriptList.length; | |
| for(i=0; i<len; i++){ //for each required script | |
| url = getFullUrl(scriptList[i]); | |
| if(!isLoaded(url)){ //if there is not already a script element with this URL in the document | |
| appendScript(url, onLoad, onFailure); //append a script element to <head> | |
| pending.push(url); | |
| } | |
| } | |
| function onLoad(evt){ | |
| if(!this.readyState || this.readyState === "loaded" || this.readyState === "complete"){ | |
| delete this.onreadystatechange; | |
| delete this.onload; | |
| pending.splice(pending.indexOf(this.src), 1); | |
| if(!pending.length){ | |
| onSuccess(); | |
| } | |
| } | |
| } | |
| } | |
| function getFullUrl(url){ | |
| var loc, path; | |
| url = ""+url; | |
| if(/^https?:\/\//i.test(url)){ | |
| return url; | |
| } | |
| loc = document.location; | |
| if(url.slice(0, 2) === "//"){ | |
| return loc.protocol+url; | |
| } | |
| else if(url[0] === "/"){ | |
| return loc.protocol+"//"+loc.host+url; | |
| } | |
| else{ | |
| path = loc.pathname.replace(/\/[^\/]*$/, "/"); | |
| while(url.slice(0, 3) === "../"){ | |
| path = path.replace(/\/[^\/]*\/$/, "/"); | |
| url = url.slice(3); | |
| } | |
| return loc.protocol+"//"+loc.host+path+url; | |
| } | |
| } | |
| function isLoaded(url){ | |
| var i, len, scripts = Array.prototype.slice.call(document.getElementsByTagName("script")); | |
| len = scripts.length; | |
| for(i=0; i<len; i++){ | |
| //if(getFullUrl(scripts[i].src) === url) return true; | |
| if(scripts[i].src === url) return true; | |
| } | |
| return false; | |
| } | |
| function appendScript(url, onLoad, onError){ | |
| var script = document.createElement("script"); | |
| script.type = "text/javascript"; | |
| script.src = url; | |
| script.onreadystatechange = onLoad; | |
| script.onload = onLoad; | |
| script.onerror = onError /*|| function (evt){ throw new Error("Required script failed to load: "+url); }*/; | |
| head.appendChild(script); | |
| } | |
| return require; | |
| })(); |
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