我如何等待附加到正文的 <script> 完成执行

Question

当用户单击一个按钮时，我需要将一个外部脚本附加到我的正文中。这是要求。

菜鸟问题。假设外部库创建了一个 window.newLib 变量。当 newLib 变量可供我使用时如何通知我？

我试过了但是没有调用 onload：

  const script = document.createElement('script');
  script.innerHTML = 'window.test = 1; console.log("test defined.");';
  script.onload = "console.log('onload called.', window.test)"
  script.async = false;
  document.body.appendChild(script);

这行得通，但我觉得它很脏。有没有更好的方法？

const injectScript = () => {
  const script = document.createElement('script');
  script.innerHTML = 'setTimeout(() => {window.test = 1},10500); console.log("test defined.");';
  script.async = false;
  document.body.appendChild(script);
}

const nap = ms => new Promise(res => setTimeout(res, ms));

const maxAttempts = 100;
const msNap = 100; // 10s timeout

const start = async () => {
  injectScript();
  let id = 0;
  while (true) {
    if (++id === maxAttempts) {
      throw(`Lib took too long to load: ${id * msNap}ms`);
    }
    if (window.test) break;
    await nap(msNap);
  }
  console.log('External lib correctly loaded.');
};
start();

Answer 1

感谢@Ultimater。这似乎按预期工作：

const script = document.createElement('script');
script.src = 'data:text/html,id = 0;while(true){ if(++id==1000000) break;} window.test = 1; console.log("test defined.");';
script.onload = () => console.log('onload called.', window.test);
document.body.appendChild(script);

Answer 2

试试这个：

const injectScript = () => {
        const script = document.createElement('script');
        script.innerHTML = 'console.log("Function loaded..."); window.postMessage({cmd:"loaded"});';
        script.async = false;
        document.body.appendChild(script);
        }

        setTimeout(injectScript, 3000);

        window.addEventListener('message', function(e){
            if(e.data.cmd === 'loaded'){
                console.log('external library loaded');
            }
        });

我如何等待附加到正文的 <script> 完成执行

How can I wait for <script> appended to body to finish executing

html

javascript

script-tag

async-await

ios-web-app