我如何在另一个JavaScript文件中添加一个JavaScript文件,类似于CSS中的 @import?
当前回答
使用 ES6 的进口和出口模块与 Node.js 合作
使用.mjs 扩展而不是.js 的名称文件
创建文件
touch main.mjs lib.mjs
主.js
import { add } from './lib.mjs';
console.log(add(40, 2));
英格兰MJ
export let add = (x,y) => {
return x + y
}
跑步
node --experimental-modules main.js
其他回答
我的总体解决方案来自EdgeS的effect.js.st图书馆(我写的)。
无情的插件警报 - 我在其他 stackexchange 网络网站上. 这是一个链接到 https://codereview.stackexchange.com/questions/263764/dynamic-load-css-or-script。
您将使用什么代码或设计来支持CSS和脚本的动态加载?
要求
支持承诺-等待-async 包括错误操作支持负载一次加密,包括重新加载支持负载在头部,身体,或当前的脚本元素支持负载 css,js,mjs 模块或其他脚本类型的支持其他标签特,如 nonce,crossorigin 等
static loadScriptOrStyle(url, options) {
// provenance :<# **Smallscript EdgeS efekt** `efekt.js.st` github libraries #>
// returns :<Promise#onload;onerror>
// options :<# `fIgnoreCache`, `fAppendToHead`, `fUrlIsStyle`, `attrs:{}` #>
const head = document.head; let node = options?.fAppendToBody ? document.body : head;
const url_loader_cache = document.head.url_loader_cache
? head.url_loader_cache
: (head.url_loader_cache = {script:{},link:{}})
const kind = (options?.fUrlIsStyle || /\.css(?:(?:\?|#).*)?$/i.test(url))
? 'link' : 'script';
// check already-loaded cache
if(url_loader_cache[kind][url]) {
const el = url_loader_cache[kind][url];
// support `fIgnoreCache` reload-option; should not use on `head`
if(options?.fIgnoreCache)
el.remove();
else
return(new CustomEvent('cache',{detail:el}));
}
// (re)create and record it
const self = document.currentScript;
const el = url_loader_cache[kind][url] = document.createElement(kind);
const append = (!self || options?.fAppendToHead || options?.fAppendToBody)
? el => node.appendChild(el)
: el => self.parentNode.insertBefore(el, self);
const load = new Promise((resolve, reject) => {
el.onload = e => {e.detail = el;resolve(e)};
el.onerror = e => {e.detail = el;reject(e)};
// `onload` or `onerror` possibly alter `cache` value
// throw(new URIError(`The ${url} didn't load correctly.`))
});
// configure `module` attr, as appropriate
if(/\.mjs(?:(?:\?|#).*)?$/i.test(url))
el.type = 'module'
// configure other attrs as appropriate (referrer, nonce, etc)
for(const key in options?.attrs) {el[key] = attrs[key]}
// trigger it
if(kind === 'link') el.rel = 'stylesheet', el.href = url; else el.src = url;
append(el);
return(load);
}
旧版本的JavaScript没有进口,包括,或要求,所以许多不同的方法对这个问题已经开发。
使用 package.json:
{
"type": "module"
}
export function hello() {
return "Hello";
}
import { hello } from './module.js';
let val = hello(); // val is "Hello";
export function hello() {
return "Hello";
}
此分類上一篇:mjs:
import { hello } from './module.mjs';
let val = hello(); // val is "Hello";
ECMAScript 在浏览器中的模块
<script type="module">
import { hello } from './hello.mjs'; // Or the extension could be just `.js`
hello('world');
</script>
// hello.mjs -- or the extension could be just `.js`
export function hello(text) {
const div = document.createElement('div');
div.textContent = `Hello ${text}`;
document.body.appendChild(div);
}
在浏览器中的动态进口
<script type="module">
import('hello.mjs').then(module => {
module.hello('world');
});
</script>
Node.js 需要
// mymodule.js
module.exports = {
hello: function() {
return "Hello";
}
}
// server.js
const myModule = require('./mymodule');
let val = myModule.hello(); // val is "Hello"
您可以使用 AJAX 通话加载额外的脚本,然后使用 eval 运行它. 这是最简单的方式,但由于 JavaScript Sandbox 安全模式而仅限于您的域名。
fetchInject([
'https://cdn.jsdelivr.net/momentjs/2.17.1/moment.min.js'
]).then(() => {
console.log(`Finish in less than ${moment().endOf('year').fromNow(true)}`)
})
jQuery 图书馆在一个行中提供充电功能:
$.getScript("my_lovely_script.js", function() {
alert("Script loaded but not necessarily executed.");
});
下面是如何工作的例子:
function dynamicallyLoadScript(url) {
var script = document.createElement("script"); // create a script DOM node
script.src = url; // set its src to the provided URL
document.head.appendChild(script); // add it to the end of the head section of the page (could change 'head' to 'body' to add it to the end of the body section instead)
}
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.head;
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);
}
然后,你写下你想要使用的代码后,脚本被加载到一个Lambda函数:
var myPrettyCode = function() {
// Here, do whatever you want
};
loadScript("my_lovely_script.js", myPrettyCode);
请注意,在 DOM 已加载后,脚本可以运行,或者在此之前,取决于浏览器,以及您是否包含了行 script.async = false;. 有一个关于JavaScript 加载的一般文章,讨论了这一点。
源代码合并/预处理
保持它好,短,简单,可持续的! :]
// Third-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]);
}
}
这个代码只是一个短暂的功能例子,可能需要额外的功能功能,以便在任何(或提供)平台上提供完整的支持。
我只是写了这个JavaScript代码(使用DOM操作的Prototype):
var require = (function() {
var _required = {};
return (function(url, callback) {
if (typeof url == 'object') {
// We've (hopefully) got an array: time to chain!
if (url.length > 1) {
// Load the nth file as soon as everything up to the
// n-1th one is done.
require(url.slice(0, url.length - 1), function() {
require(url[url.length - 1], callback);
});
} else if (url.length == 1) {
require(url[0], callback);
}
return;
}
if (typeof _required[url] == 'undefined') {
// Haven't loaded this URL yet; gogogo!
_required[url] = [];
var script = new Element('script', {
src: url,
type: 'text/javascript'
});
script.observe('load', function() {
console.log("script " + url + " loaded.");
_required[url].each(function(cb) {
cb.call(); // TODO: does this execute in the right context?
});
_required[url] = true;
});
$$('head')[0].insert(script);
} else if (typeof _required[url] == 'boolean') {
// We already loaded the thing, so go ahead.
if (callback) {
callback.call();
}
return;
}
if (callback) {
_required[url].push(callback);
}
});
})();
使用:
<script src="prototype.js"></script>
<script src="require.js"></script>
<script>
require(['foo.js','bar.js'], function () {
/* Use foo.js and bar.js here */
});
</script>
地址: http://gist.github.com/284442.
此脚本将添加 JavaScript 文件到任何其他 <script> 标签的顶部:
(function () {
var li = document.createElement('script');
li.type = 'text/javascript';
li.src = "http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js";
li.async = true;
var s = document.getElementsByTagName('script')[0];
s.parentNode.insertBefore(li, s);
})();