动态加载JavaScript文件
如何可靠地动态加载JavaScript文件？这将用于实现一个模块或组件，当“初始化”该组件时，该组件将根据需要动态加载所有需要的JavaScript库脚本 使用该组件的客户端不需要加载实现该组件的所有库脚本文件（并将动态加载JavaScript文件,javascript,file,import,include,Javascript,File,Import,Include,如何可靠地动态加载JavaScript文件？这将用于实现一个模块或组件，当“初始化”该组件时，该组件将根据需要动态加载所有需要的JavaScript库脚本 使用该组件的客户端不需要加载实现该组件的所有库脚本文件（并将标记手动插入其网页），只需加载“主”组件脚本文件即可 主流JavaScript库（Prototype、jQuery等）是如何做到这一点的？这些工具是否将多个JavaScript文件合并到一个脚本文件的可再发行“构建”版本中？或者他们会动态加载辅助“库”脚本吗 对该问题的补充：在加载动
文档。请观察文档范围内的事件。例如：
document.observe("dom:loaded", function() {
// initially hide all containers for tab content
$$('div.tabcontent').invoke('hide');
});
脚本元素的可用事件有哪些？以下是我找到的一些示例代码。。。有人有更好的方法吗
function include(url)
{
var s = document.createElement("script");
s.setAttribute("type", "text/javascript");
s.setAttribute("src", url);
var nodes = document.getElementsByTagName("*");
var node = nodes[nodes.length -1].parentNode;
node.appendChild(s);
}
所有主要的javascript库，如jscript、prototype和YUI都支持加载脚本文件。例如，在YUI中，加载core后，可以执行以下操作来加载calendar控件
var loader = new YAHOO.util.YUILoader({
require: ['calendar'], // what components?
base: '../../build/',//where do they live?
//filter: "DEBUG", //use debug versions (or apply some
//some other filter?
//loadOptional: true, //load all optional dependencies?
//onSuccess is the function that YUI Loader
//should call when all components are successfully loaded.
onSuccess: function() {
//Once the YUI Calendar Control and dependencies are on
//the page, we'll verify that our target container is
//available in the DOM and then instantiate a default
//calendar into it:
YAHOO.util.Event.onAvailable("calendar_container", function() {
var myCal = new YAHOO.widget.Calendar("mycal_id", "calendar_container");
myCal.render();
})
},
// should a failure occur, the onFailure function will be executed
onFailure: function(o) {
alert("error: " + YAHOO.lang.dump(o));
}
});
// Calculate the dependency and insert the required scripts and css resources
// into the document
loader.insert();
我做的基本上和你做的一样，亚当，但是做了一点小小的修改，以确保我是附加在头标签上完成工作的。我只是创建了一个include函数（下面的代码）来处理脚本和css文件
此函数还检查以确保脚本或CSS文件尚未动态加载。它不检查手工编码的值，可能有更好的方法，但它达到了目的
function include( url, type ){
// First make sure it hasn't been loaded by something else.
if( Array.contains( includedFile, url ) )
return;
// Determine the MIME-type
var jsExpr = new RegExp( "js$", "i" );
var cssExpr = new RegExp( "css$", "i" );
if( type == null )
if( jsExpr.test( url ) )
type = 'text/javascript';
else if( cssExpr.test( url ) )
type = 'text/css';
// Create the appropriate element.
var tag = null;
switch( type ){
case 'text/javascript' :
tag = document.createElement( 'script' );
tag.type = type;
tag.src = url;
break;
case 'text/css' :
tag = document.createElement( 'link' );
tag.rel = 'stylesheet';
tag.type = type;
tag.href = url;
break;
}
// Insert it to the <head> and the array to ensure it is not
// loaded again.
document.getElementsByTagName("head")[0].appendChild( tag );
Array.add( includedFile, url );
}
函数包括（url、类型）{
//首先确保它没有被其他东西加载。
if（Array.contains（includedFile，url））
返回；
//确定MIME类型
var jsExpr=newregexp（“js$”，“i”）；
var cssExpr=newregexp（“css$”，“i”）；
if（type==null）
if（jsExpr.test（url））
类型='text/javascript'；
else if（cssExpr.test（url））
类型='text/css'；
//创建适当的元素。
var-tag=null；
开关（类型）{
案例“text/javascript”：
tag=document.createElement（'script'）；
tag.type=type；
tag.src=url；
打破
案例“文本/css”：
tag=document.createElement（'link'）；
tag.rel='stylesheet'；
tag.type=type；
tag.href=url；
打破
}
//将其插入到和数组中，以确保
//再次加载。
document.getElementsByTagName（“head”）[0].appendChild（标记）；
add（包括文件、url）；
}
有人有更好的方法吗
function include(url)
{
var s = document.createElement("script");
s.setAttribute("type", "text/javascript");
s.setAttribute("src", url);
var nodes = document.getElementsByTagName("*");
var node = nodes[nodes.length -1].parentNode;
node.appendChild(s);
}
我认为将脚本添加到正文中比将其添加到页面上的最后一个节点更容易。这个怎么样：
function include(url) {
var s = document.createElement("script");
s.setAttribute("type", "text/javascript");
s.setAttribute("src", url);
document.body.appendChild(s);
}
我们在工作中使用的技术是使用AJAX请求请求javascript文件，然后对返回进行eval（）。如果您使用的是prototype库，那么他们在其Ajax.Request调用中支持此功能。我使用了一个：
var js=[“scripts/jquery.dimensions.js”、“scripts/shadedborder.js”、“scripts/jqmodal.js”、“scripts/main.js”]；
var$head=$（“head”）；
对于（var i=0；i
它在我测试过的每一款浏览器中都运行良好：IE6/7、Firefox、Safari和Opera
更新：jQuery-less版本：
<script>
var js = ["scripts/jquery.dimensions.js", "scripts/shadedborder.js", "scripts/jqmodal.js", "scripts/main.js"];
for (var i = 0, l = js.length; i < l; i++) {
document.getElementsByTagName("head")[0].innerHTML += ("<script src=\"" + js[i] + "\"></scr" + "ipt>");
}
</script>
var js=[“scripts/jquery.dimensions.js”、“scripts/shadedborder.js”、“scripts/jqmodal.js”、“scripts/main.js”]；
for（var i=0，l=js.length；i
我使用了在网上找到的另一种解决方案。。。这一个在creativecommons下，它在调用函数之前检查源文件是否包括在内
您可以在此处找到该文件：
/**include-包括来自js的.js文件-bfults@gmail.com - 2005-02-09
**根据知识共享署名共享许可证许可的代码
** http://creativecommons.org/licenses/by-sa/2.0/
**/
var hIncludes=null；
功能包括（sURI）
{
if（document.getElementsByTagName）
{
如果（！hIncludes）
{
hIncludes={}；
var cScripts=document.getElementsByTagName（“脚本”）；
对于（变量i=0，len=cScripts.length；i
您可以编写动态脚本标记（使用）：
这里的问题是，我们不知道外部脚本文件何时完全加载
我们通常希望我们的依赖代码位于下一行，并喜欢编写如下内容：
if (iNeedSomeMore) {
Script.load("myBigCodeLibrary.js"); // includes code for myFancyMethod();
myFancyMethod(); // cool, no need for callbacks!
}
有一种智能的方法可以在不需要回调的情况下注入脚本依赖项。您只需通过同步AJAX请求提取脚本，并在全局级别评估脚本
如果使用Prototype，则Script.load方法如下所示：
var Script = {
_loadedScripts: [],
include: function(script) {
// include script only once
if (this._loadedScripts.include(script)) {
return false;
}
// request file synchronous
var code = new Ajax.Request(script, {
asynchronous: false,
method: "GET",
evalJS: false,
evalJSON: false
}).transport.responseText;
// eval code on global level
if (Prototype.Browser.IE) {
window.execScript(code);
} else if (Prototype.Browser.WebKit) {
$$("head").first().insert(Object.extend(
new Element("script", {
type: "text/javascript"
}), {
text: code
}
));
} else {
window.eval(code);
}
// remember included script
this._loadedScripts.push(script);
}
};
刚刚发现了中的一个很棒的特性（在撰写本文时，可在预览版中获得）。您可以轻松地将依赖项插入YUI库和“外部”模块（您正在寻找的模块），而无需太多代码：
它还回答了关于加载外部模块后立即调用函数的第二个问题
例如：
YUI({
modules: {
'simple': {
fullpath: "http://example.com/public/js/simple.js"
},
'complicated': {
fullpath: "http://example.com/public/js/complicated.js"
requires: ['simple'] // <-- dependency to 'simple' module
}
},
timeout: 10000
}).use('complicated', function(Y, result) {
// called as soon as 'complicated' is loaded
if (!result.success) {
// loading failed, or timeout
handleError(result.msg);
} else {
// call a function that needs 'complicated'
doSomethingComplicated(...);
}
});
YUI({
模块：{
“简单”：{
完整路径：“http://example.com/public/js/simple.js"
},
“复杂的”：{
完整路径
var Script = {
_loadedScripts: [],
include: function(script) {
// include script only once
if (this._loadedScripts.include(script)) {
return false;
}
// request file synchronous
var code = new Ajax.Request(script, {
asynchronous: false,
method: "GET",
evalJS: false,
evalJSON: false
}).transport.responseText;
// eval code on global level
if (Prototype.Browser.IE) {
window.execScript(code);
} else if (Prototype.Browser.WebKit) {
$$("head").first().insert(Object.extend(
new Element("script", {
type: "text/javascript"
}), {
text: code
}
));
} else {
window.eval(code);
}
// remember included script
this._loadedScripts.push(script);
}
};
YUI({
modules: {
'simple': {
fullpath: "http://example.com/public/js/simple.js"
},
'complicated': {
fullpath: "http://example.com/public/js/complicated.js"
requires: ['simple'] // <-- dependency to 'simple' module
}
},
timeout: 10000
}).use('complicated', function(Y, result) {
// called as soon as 'complicated' is loaded
if (!result.success) {
// loading failed, or timeout
handleError(result.msg);
} else {
// call a function that needs 'complicated'
doSomethingComplicated(...);
}
});
/*
* FILENAME : project.library.js
* USAGE : loads any javascript library
*/
var dirPath = "../js/";
var library = ["functions.js","swfobject.js","jquery.jeditable.mini.js","jquery-ui-1.8.8.custom.min.js","ui/jquery.ui.core.min.js","ui/jquery.ui.widget.min.js","ui/jquery.ui.position.min.js","ui/jquery.ui.button.min.js","ui/jquery.ui.mouse.min.js","ui/jquery.ui.dialog.min.js","ui/jquery.effects.core.min.js","ui/jquery.effects.blind.min.js","ui/jquery.effects.fade.min.js","ui/jquery.effects.slide.min.js","ui/jquery.effects.transfer.min.js"];
for(var script in library){
$('head').append('<script type="text/javascript" src="' + dirPath + library[script] + '"></script>');
}
<script type="text/javascript" src="project.library.js"></script>
$.getScript("my_lovely_script.js", function(){
alert("Script loaded and executed.");
// here you can use anything you defined in the loaded script
});
var js = document.createElement("script");
js.type = "text/javascript";
js.src = jsFilePath;
document.body.appendChild(js);
var s = new MySuperObject();
Error : MySuperObject is undefined
function loadScript(url, callback)
{
// adding the script tag to the head as suggested before
var head = document.getElementsByTagName('head')[0];
var script = document.createElement('script');
script.type = 'text/javascript';
script.src = url;
// then bind the event to the callback function
// there are several events for cross browser compatibility
script.onreadystatechange = callback;
script.onload = callback;
// fire the loading
head.appendChild(script);
}
var myPrettyCode = function() {
// here, do what ever you want
};
loadScript("my_lovely_script.js", myPrettyCode);
$.getScript("my_lovely_script.js", function() {
alert("Script loaded and executed.");
// here you can use anything you defined in the loaded script
});
var _rmod = _rmod || {}; //require module namespace
_rmod.on_ready_fn_stack = [];
_rmod.libpath = '';
_rmod.imported = {};
_rmod.loading = {
scripts: {},
length: 0
};
_rmod.findScriptPath = function(script_name) {
var script_elems = document.getElementsByTagName('script');
for (var i = 0; i < script_elems.length; i++) {
if (script_elems[i].src.endsWith(script_name)) {
var href = window.location.href;
href = href.substring(0, href.lastIndexOf('/'));
var url = script_elems[i].src.substring(0, script_elems[i].length - script_name.length);
return url.substring(href.length+1, url.length);
}
}
return '';
};
_rmod.libpath = _rmod.findScriptPath('script.js'); //Path of your main script used to mark the root directory of your library, any library
_rmod.injectScript = function(script_name, uri, callback, prepare) {
if(!prepare)
prepare(script_name, uri);
var script_elem = document.createElement('script');
script_elem.type = 'text/javascript';
script_elem.title = script_name;
script_elem.src = uri;
script_elem.async = true;
script_elem.defer = false;
if(!callback)
script_elem.onload = function() {
callback(script_name, uri);
};
document.getElementsByTagName('head')[0].appendChild(script_elem);
};
_rmod.requirePrepare = function(script_name, uri) {
_rmod.loading.scripts[script_name] = uri;
_rmod.loading.length++;
};
_rmod.requireCallback = function(script_name, uri) {
_rmod.loading.length--;
delete _rmod.loading.scripts[script_name];
_rmod.imported[script_name] = uri;
if(_rmod.loading.length == 0)
_rmod.onReady();
};
_rmod.onReady = function() {
if (!_rmod.LOADED) {
for (var i = 0; i < _rmod.on_ready_fn_stack.length; i++){
_rmod.on_ready_fn_stack[i]();
});
_rmod.LOADED = true;
}
};
//you can rename based on your liking. I chose require, but it can be called include or anything else that is easy for you to remember or write, except import because it is reserved for future use.
var require = function(script_name) {
var np = script_name.split('.');
if (np[np.length-1] === '*') {
np.pop();
np.push('_all');
}
script_name = np.join('.');
var uri = _rmod.libpath + np.join('/')+'.js';
if (!_rmod.loading.scripts.hasOwnProperty(script_name)
&& !_rmod.imported.hasOwnProperty(script_name)) {
_rmod.injectScript(script_name, uri,
_rmod.requireCallback,
_rmod.requirePrepare);
}
};
var ready = function(fn) {
_rmod.on_ready_fn_stack.push(fn);
};
// ----- USAGE -----
require('ivar.util.array');
require('ivar.util.string');
require('ivar.net.*');
ready(function(){
//do something when required scripts are loaded
});
/*sample requires an additional method for array prototype:*/
if (Array.prototype.contains === undefined) {
Array.prototype.contains = function (obj) {
var i = this.length;
while (i--) { if (this[i] === obj) return true; }
return false;
};
};
/*define object that will wrap our logic*/
var ScriptLoader = {
LoadedFiles: [],
LoadFile: function (url) {
var self = this;
if (this.LoadedFiles.contains(url)) return;
var xhr = new XMLHttpRequest();
xhr.onload = function () {
if (xhr.readyState === 4) {
if (xhr.status === 200) {
self.LoadedFiles.push(url);
self.AddScript(xhr.responseText);
} else {
if (console) console.error(xhr.statusText);
}
}
};
xhr.open("GET", url, false);/*last parameter defines if call is async or not*/
xhr.send(null);
},
AddScript: function (code) {
var oNew = document.createElement("script");
oNew.type = "text/javascript";
oNew.textContent = code;
document.getElementsByTagName("head")[0].appendChild(oNew);
}
};
/*Load script file. ScriptLoader will check if you try to load a file that has already been loaded (this check might be better, but I'm lazy).*/
ScriptLoader.LoadFile("Scripts/jquery-2.0.1.min.js");
ScriptLoader.LoadFile("Scripts/jquery-2.0.1.min.js");
/*this will be executed right after upper lines. It requires jquery to execute. It requires a HTML input with id "tb1"*/
$(function () { alert($('#tb1').val()); });
// 3rd party plugins / script (don't forget the full path is necessary)
var FULL_PATH = '', s =
[
FULL_PATH + 'plugins/script.js' // Script example
FULL_PATH + 'plugins/jquery.1.2.js', // jQuery Library
FULL_PATH + 'plugins/crypto-js/hmac-sha1.js', // CryptoJS
FULL_PATH + 'plugins/crypto-js/enc-base64-min.js' // CryptoJS
];
function load(url)
{
var ajax = new XMLHttpRequest();
ajax.open('GET', url, false);
ajax.onreadystatechange = function ()
{
var script = ajax.response || ajax.responseText;
if (ajax.readyState === 4)
{
switch(ajax.status)
{
case 200:
eval.apply( window, [script] );
console.log("library loaded: ", url);
break;
default:
console.log("ERROR: library not loaded: ", url);
}
}
};
ajax.send(null);
}
// initialize a single load
load('plugins/script.js');
// initialize a full load of scripts
if (s.length > 0)
{
for (i = 0; i < s.length; i++)
{
load(s[i]);
}
}
document.write("<script src='https://www.google.com/recaptcha/api.js'></script>");
function loadScript(url, callback) {
var script = document.createElement("script")
script.type = "text/javascript";
if (script.readyState) { //IE
script.onreadystatechange = function () {
if (script.readyState == "loaded" || script.readyState == "complete") {
script.onreadystatechange = null;
callback();
}
};
} else { //Others
script.onload = function () {
callback();
};
}
script.src = url;
document.getElementsByTagName("head")[0].appendChild(script);
}
loadScript("https://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js", function () {
//jQuery loaded
console.log('jquery loaded');
});
[
'script1.js',
'script2.js',
'script3.js',
'script4.js'
].forEach(function(src) {
var script = document.createElement('script');
script.src = src;
script.async = false;
document.head.appendChild(script);
});
var scripts = [
'script1.js',
'script2.js',
'script3.js',
'script4.js'
];
var src;
var script;
var pendingScripts = [];
var firstScript = document.scripts[0];
// Watch scripts load in IE
function stateChange() {
// Execute as many scripts in order as we can
var pendingScript;
while (pendingScripts[0] && pendingScripts[0].readyState == 'loaded') {
pendingScript = pendingScripts.shift();
// avoid future loading events from this script (eg, if src changes)
pendingScript.onreadystatechange = null;
// can't just appendChild, old IE bug if element isn't closed
firstScript.parentNode.insertBefore(pendingScript, firstScript);
}
}
// loop through our script urls
while (src = scripts.shift()) {
if ('async' in firstScript) { // modern browsers
script = document.createElement('script');
script.async = false;
script.src = src;
document.head.appendChild(script);
}
else if (firstScript.readyState) { // IE<10
// create a script and add it to our todo pile
script = document.createElement('script');
pendingScripts.push(script);
// listen for state changes
script.onreadystatechange = stateChange;
// must set src AFTER adding onreadystatechange listener
// else we’ll miss the loaded event for cached scripts
script.src = src;
}
else { // fall back to defer
document.write('<script src="' + src + '" defer></'+'script>');
}
}
!function(e,t,r){function n(){for(;d[0]&&"loaded"==d[0][f];)c=d.shift(),c[o]=!i.parentNode.insertBefore(c,i)}for(var s,a,c,d=[],i=e.scripts[0],o="onreadystatechange",f="readyState";s=r.shift();)a=e.createElement(t),"async"in i?(a.async=!1,e.head.appendChild(a)):i[f]?(d.push(a),a[o]=n):e.write("<"+t+' src="'+s+'" defer></'+t+">"),a.src=s}(document,"script",[
"//other-domain.com/1.js",
"2.js"
])
<script>
$(document).ready(function() {
$('body').append('<script src="https://maps.googleapis.com/maps/api/js?key=KEY&libraries=places&callback=getCurrentPickupLocation" async defer><\/script>');
});
</script>
getScriptOnce("url_of_your_JS_file.js");
const moduleSpecifier = './dir/someModule.js';
import(moduleSpecifier)
.then(someModule => someModule.foo()); // executes foo method in someModule
await new Promise((resolve, reject) => {let js = document.createElement("script"); js.src="mylibrary.js"; js.onload=resolve; js.onerror=reject; document.body.appendChild(js)});
(async () => {
await import('./synth/BubbleSynth.js')
})()
(async () => {
await import('./synth/BubbleSynth.js').catch((error) => console.log('Loading failed' + error))
})()
$(document).ready(function(){
if (Array.prototype.contains === undefined) {
Array.prototype.contains = function (obj) {
var i = this.length;
while (i--) { if (this[i] === obj) return true; }
return false;
};
};
/* define object that will wrap our logic */
var jsScriptCssLoader = {
jsExpr : new RegExp( "js$", "i" ),
cssExpr : new RegExp( "css$", "i" ),
loadedFiles: [],
loadFile: function (cssJsFileArray) {
var self = this;
// remove duplicates with in array
cssJsFileArray.filter((item,index)=>cssJsFileArray.indexOf(item)==index)
var loadedFileArray = this.loadedFiles;
$.each(cssJsFileArray, function( index, url ) {
// if multiple arrays are loaded the check the uniqueness
if (loadedFileArray.contains(url)) return;
if( self.jsExpr.test( url ) ){
$.get(url, function(data) {
self.addScript(data);
});
}else if( self.cssExpr.test( url ) ){
$.get(url, function(data) {
self.addCss(data);
});
}
self.loadedFiles.push(url);
});
// don't load twice accross different arrays
},
addScript: function (code) {
var oNew = document.createElement("script");
oNew.type = "text/javascript";
oNew.textContent = code;
document.getElementsByTagName("head")[0].appendChild(oNew);
},
addCss: function (code) {
var oNew = document.createElement("style");
oNew.textContent = code;
document.getElementsByTagName("head")[0].appendChild(oNew);
}
};
//jsScriptCssLoader.loadFile(["css/1.css","css/2.css","css/3.css"]);
jsScriptCssLoader.loadFile(["js/common/1.js","js/2.js","js/common/file/fileReader.js"]);
});
const loadCDN = src =>
new Promise((resolve, reject) => {
if (document.querySelector(`head > script[src="${src}"]`) !== null) return resolve()
const script = document.createElement("script")
script.src = src
script.async = true
document.head.appendChild(script)
script.onload = resolve
script.onerror = reject
})
await loadCDN("https://.../script.js")
loadCDN("https://.../script.js").then(res => {}).catch(err => {})
import('./myscript.js');
fetch('myscript.js').then(r => r.text()).then(t => new Function(t)());
//Create a script element that will load
let dynamicScript = document.createElement('script');
//Set source to the script we need to load
dynamicScript.src = 'linkToNeededJsFile.js';
//Set onload to callback function that depends on this script or do inline as shown below
dynamicScript.onload = () => {
//Code that depends on the loaded script should be here
};
//append the created script element to body element
document.body.append(dynamicScript);
$.getScript('linkToNeededJsFile.js', () => {
//Code that depends on the loaded script should be here
});