javascript - 如何在 Angular 中动态加载外部脚本？

Question

我有这个模块，无需添加 <script> 即可将外部库与附加逻辑一起组件化。直接标记到 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 import ES6 规范是静态的，并在 TypeScript 转译期间而不是在运行时解析。

无论如何使其可配置，以便 file.js 将从 CDN 或本地文件夹加载？如何告诉 Angular 2 动态加载脚本？

Answer 1

您可以使用以下技术来在 Angular 项目中按需动态加载 JS 脚本和库。

script.store.ts 将包含本地或远程服务器上脚本的路径，以及将使用的名称动态加载脚本

 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(inject)的服务，它将处理脚本的加载，按原样复制 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);
        }
    });
}

}

在你需要的地方注入(inject)这个 ScriptService 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));