如何在 Angular 中动态加载外部 JavaScript 文件？

如何在 Angular 中动态加载外部脚本

如您所知，Angular 中使用的 ES6 导入功能是静态的，并且在 Angular 中解析打字稿编译。要根据配置动态加载脚本，您可以采用以下技术。

在 script.store.ts 中，定义包含脚本名称和路径的 JavaScript 文件对象数组：

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 将处理脚本加载逻辑：

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);
        }
    });
}

}

注入ScriptService并使用它动态加载脚本：

this.script.load('filepicker', 'rangeSlider').then(data => {
    console.log('script loaded ', data);
}).catch(error => console.log(error));

此技术允许您根据您的配置动态加载脚本，来自 CDN 或本地文件路径。

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