Angular的通用解决方案;在加载播放视频的脚本之前，我需要等待页面上的特定元素。

import {Inject, Injectable, PLATFORM_ID} from '@angular/core';
import {isPlatformBrowser} from "@angular/common";

@Injectable({
  providedIn: 'root'
})
export class ScriptLoaderService {

  constructor(
    @Inject(PLATFORM_ID) private platformId: Object,
  ) {
  }

  load(scriptUrl: string) {
    if (isPlatformBrowser(this.platformId)) {
      let node: any = document.createElement('script');
      node.src = scriptUrl;
      node.type = 'text/javascript';
      node.async = true;
      node.charset = 'utf-8';
      document.getElementsByTagName('head')[0].appendChild(node);
    }
  }
}

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

如果你正在使用system.js，你可以在运行时使用System.import():

export class MyAppComponent {
  constructor(){
    System.import('path/to/your/module').then(refToLoadedModule => {
      refToLoadedModule.someFunction();
    }
  );
}

如果你正在使用webpack，你可以充分利用它强大的代码分割支持。确保:

export class MyAppComponent {
  constructor() {
     require.ensure(['path/to/your/module'], require => {
        let yourModule = require('path/to/your/module');
        yourModule.someFunction();
     }); 
  }
}

这可能有用。这段代码动态地将<script>标记附加到单击按钮时的html文件头部。

const url = 'http://iknow.com/this/does/not/work/either/file.js';

export class MyAppComponent {
    loadAPI: Promise<any>;

    public buttonClicked() {
        this.loadAPI = new Promise((resolve) => {
            console.log('resolving promise...');
            this.loadScript();
        });
    }

    public loadScript() {
        console.log('preparing to load...')
        let node = document.createElement('script');
        node.src = url;
        node.type = 'text/javascript';
        node.async = true;
        node.charset = 'utf-8';
        document.getElementsByTagName('head')[0].appendChild(node);
    }
}

@ rahull -kumar的解决方案对我来说很好，但我想在我的typescript中调用我的javascript函数

foo.myFunctions() // works in browser console, but foo can't be used in typescript file

我通过在我的typescript中声明它来修复它:

import { Component } from '@angular/core';
import { ScriptService } from './script.service';
declare var foo;

现在，我可以在typcript文件的任何地方调用foo

对于那些也想动态加载样式的人。 (基于@Rahul Kumar的精彩回答)

script.store.ts

interface Scripts {
    name: string;
    src: string;
}

export const StyleStore: Scripts[] = [
    { name: 'fancybox-css', src: 'https://cdn.jsdelivr.net/gh/fancyapps/fancybox@3.5.7/dist/jquery.fancybox.min.css' }
];

export const ScriptStore: Scripts[] = [
    { name: 'jquery', src: 'https://cdn.jsdelivr.net/npm/jquery@3.5.1/dist/jquery.min.js' },
    { name: 'other', src: '[other script source]'}
];

script-loader.service.ts

import { Injectable } from '@angular/core';
import { ScriptStore, StyleStore } from '../../stores/script.store';

@Injectable({
  providedIn: 'root'
})
export class ScriptLoaderService {

  private scripts: any = {};
  private styles: any = {};

  constructor() {
    ScriptStore.forEach((script: any) => {
      this.scripts[script.name] = {
        loaded: false,
        src: script.src
      };
    });

    StyleStore.forEach((script: any) => {
      this.styles[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);
  }

  loadStyles(...scripts: string[]) {
    var promises: any[] = [];
    scripts.forEach((script) => promises.push(this.loadStyle(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') as any;
        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);
      }
    });
  }

  loadStyle(name: string) {
    return new Promise((resolve, reject) => {
      //resolve if already loaded
      if (this.styles[name].loaded) {
        resolve({ script: name, loaded: true, status: 'Already Loaded' });
      }
      else {
        //load style
        let style = document.createElement('link') as any;
        style.type = "text/css";
        style.rel = "stylesheet";
        style.href = this.styles[name].src;
        if (style.readyState) {  //IE
          style.onreadystatechange = () => {
            if (style.readyState === "loaded" || style.readyState === "complete") {
              style.onreadystatechange = null;
              this.styles[name].loaded = true;
              resolve({ style: name, loaded: true, status: 'Loaded' });
            }
          };
        } else {  //Others
          style.onload = () => {
            this.styles[name].loaded = true;
            resolve({ style: name, loaded: true, status: 'Loaded' });
          };
        }
        style.onerror = (error: any) => resolve({ style: name, loaded: false, status: 'Loaded' });
        document.getElementsByTagName('head')[0].appendChild(style);
      }
    });
  }

}

app.component.ts

constructor(private scriptLoaderService: ScriptLoaderService) {
  this.scriptLoaderService.loadStyles('fancybox-css').then(x => {
    this.scriptLoaderService.load('jquery', 'fancybox').then(data => {
    }).catch(error => console.log(error));
  });
}