我有这个模块,它将外部库与额外的逻辑组件化,而不直接将<script>标记添加到index.html中:
import 'http://external.com/path/file.js'
//import '../js/file.js'
@Component({
selector: 'my-app',
template: `
<script src="http://iknow.com/this/does/not/work/either/file.js"></script>
<div>Template</div>`
})
export class MyAppComponent {...}
我注意到ES6规范的导入是静态的,并且是在TypeScript编译期间解析的,而不是在运行时。
总之,让它变得可配置,这样file。js就会从CDN或本地文件夹加载?
如何告诉Angular 2动态加载脚本?
import { Injectable } from '@angular/core';
import * as $ from 'jquery';
interface Script {
src: string;
loaded: boolean;
}
@Injectable()
export class ScriptLoaderService {
public _scripts: Script[] = [];
/**
* @deprecated
* @param tag
* @param {string} scripts
* @returns {Promise<any[]>}
*/
load(tag, ...scripts: string[]) {
scripts.forEach((src: string) => {
if (!this._scripts[src]) {
this._scripts[src] = { src: src, loaded: false };
}
});
const promises: any[] = [];
scripts.forEach(src => promises.push(this.loadScript(tag, src)));
return Promise.all(promises);
}
/**
* Lazy load list of scripts
* @param tag
* @param scripts
* @param loadOnce
* @returns {Promise<any[]>}
*/
loadScripts(tag, scripts, loadOnce?: boolean) {
debugger;
loadOnce = loadOnce || false;
scripts.forEach((script: string) => {
if (!this._scripts[script]) {
this._scripts[script] = { src: script, loaded: false };
}
});
const promises: any[] = [];
scripts.forEach(script => promises.push(this.loadScript(tag, script, loadOnce)));
return Promise.all(promises);
}
/**
* Lazy load a single script
* @param tag
* @param {string} src
* @param loadOnce
* @returns {Promise<any>}
*/
loadScript(tag, src: string, loadOnce?: boolean) {
debugger;
loadOnce = loadOnce || false;
if (!this._scripts[src]) {
this._scripts[src] = { src: src, loaded: false };
}
return new Promise((resolve, _reject) => {
// resolve if already loaded
if (this._scripts[src].loaded && loadOnce) {
resolve({ src: src, loaded: true });
} else {
// load script tag
const scriptTag = $('<script/>')
.attr('type', 'text/javascript')
.attr('src', this._scripts[src].src);
$(tag).append(scriptTag);
this._scripts[src] = { src: src, loaded: true };
resolve({ src: src, loaded: true });
}
});
}
reloadOnSessionChange() {
window.addEventListener('storage', function(data) {
if (data['key'] === 'token' && data['oldValue'] == null && data['newValue']) {
document.location.reload();
}
});
}
}
嗨,你可以使用Renderer2和elementRef只需几行代码:
constructor(private readonly elementRef: ElementRef,
private renderer: Renderer2) {
}
ngOnInit() {
const script = this.renderer.createElement('script');
script.src = 'http://iknow.com/this/does/not/work/either/file.js';
script.onload = () => {
console.log('script loaded');
initFile();
};
this.renderer.appendChild(this.elementRef.nativeElement, script);
}
onload函数可以用来在脚本加载后调用脚本函数,如果你必须在ngOnInit()中进行调用,这是非常有用的。
还有一种选择是利用scriptjs包来解决这个问题
允许您按需从任何URL加载脚本资源
例子
安装包:
npm i scriptjs
以及scriptjs的类型定义:
npm install --save @types/scriptjs
然后导入$script.get()方法:
import { get } from 'scriptjs';
最后加载脚本资源,在我们的例子中是谷歌Maps库:
export class AppComponent implements OnInit {
ngOnInit() {
get("https://maps.googleapis.com/maps/api/js?key=", () => {
//Google Maps library has been loaded...
});
}
}
Demo
我已经修改了@rahul kumars的答案,所以它使用可观察的代替:
import { Injectable } from "@angular/core";
import { Observable } from "rxjs/Observable";
import { Observer } from "rxjs/Observer";
@Injectable()
export class ScriptLoaderService {
private scripts: ScriptModel[] = [];
public load(script: ScriptModel): Observable<ScriptModel> {
return new Observable<ScriptModel>((observer: Observer<ScriptModel>) => {
var existingScript = this.scripts.find(s => s.name == script.name);
// Complete if already loaded
if (existingScript && existingScript.loaded) {
observer.next(existingScript);
observer.complete();
}
else {
// Add the script
this.scripts = [...this.scripts, script];
// Load the script
let scriptElement = document.createElement("script");
scriptElement.type = "text/javascript";
scriptElement.src = script.src;
scriptElement.onload = () => {
script.loaded = true;
observer.next(script);
observer.complete();
};
scriptElement.onerror = (error: any) => {
observer.error("Couldn't load script " + script.src);
};
document.getElementsByTagName('body')[0].appendChild(scriptElement);
}
});
}
}
export interface ScriptModel {
name: string,
src: string,
loaded: boolean
}
你可以使用以下技巧
在你的Angular项目中根据需要动态加载JS脚本和库。
ts将包含脚本在本地或远程服务器上的路径,以及用于动态加载脚本的名称
interface Scripts {
name: string;
src: string;
}
export const ScriptStore: Scripts[] = [
{name: 'filepicker', src: 'https://api.filestackapi.com/filestack.js'},
{name: 'rangeSlider', src: '../../../assets/js/ion.rangeSlider.min.js'}
];
script.service.ts是一个可注入的服务,它将处理脚本的加载,原样复制script.service.ts
import {Injectable} from "@angular/core";
import {ScriptStore} from "./script.store";
declare var document: any;
@Injectable()
export class ScriptService {
private scripts: any = {};
constructor() {
ScriptStore.forEach((script: any) => {
this.scripts[script.name] = {
loaded: false,
src: script.src
};
});
}
load(...scripts: string[]) {
var promises: any[] = [];
scripts.forEach((script) => promises.push(this.loadScript(script)));
return Promise.all(promises);
}
loadScript(name: string) {
return new Promise((resolve, reject) => {
//resolve if already loaded
if (this.scripts[name].loaded) {
resolve({script: name, loaded: true, status: 'Already Loaded'});
}
else {
//load script
let script = document.createElement('script');
script.type = 'text/javascript';
script.src = this.scripts[name].src;
if (script.readyState) { //IE
script.onreadystatechange = () => {
if (script.readyState === "loaded" || script.readyState === "complete") {
script.onreadystatechange = null;
this.scripts[name].loaded = true;
resolve({script: name, loaded: true, status: 'Loaded'});
}
};
} else { //Others
script.onload = () => {
this.scripts[name].loaded = true;
resolve({script: name, loaded: true, status: 'Loaded'});
};
}
script.onerror = (error: any) => resolve({script: name, loaded: false, status: 'Loaded'});
document.getElementsByTagName('head')[0].appendChild(script);
}
});
}
}
将这个ScriptService注入到任何你需要它的地方,并像这样加载js库
this.script.load('filepicker', 'rangeSlider').then(data => {
console.log('script loaded ', data);
}).catch(error => console.log(error));