当动态附加 Babel 时，动态附加的 JSX 不会被 Babel Standalone 转译

Question

当 Babel Standalone 作为 SCRIPT 标签的 SRC 属性提供时，Babel Standalone 可以处理动态附加的 JSX 代码。当使用 JavaScript 附加到 DOM 时，它不起作用。对于 React 库而言，情况并非如此，当动态附加 React 库时，React 库可以很好地与动态附加的 JSX 一起工作。

首先，这是 JSX 文件 (react.jsx)：

class HelloMessage extends React.Component {
  render() {
    return <h1>Hello</h1>;
  }
}
ReactDOM.render(<HelloMessage/>, document.getElementById('app'));

接下来，这里是使用它的 HTML。请注意，React 库和 JSX 文件是动态添加的；这工作正常。但是，Babel Standalone 仅在将 Babel Standalone 添加为 SCRIPT 元素的 SRC 时才转译 JSX，而不是在使用与 JS/JSX 的其余部分相同的 JavaScript 附加时。通过删除一个 Babel Standalone 调用并取消删除另一个来在两种状态之间切换。我想动态附加 Babel Standalone...有什么问题？

<!doctype html>
<html>
<head>
    <title>Inscrutable Babel Problem</title>
</head>
<body>
    <div>
        <p>Babel works only when added as a src of a SCRIPT element; it fails when the script is appended dynamically. HELLO will display below when it works.</p>
    </div>
    <div id=app></div>
<script>
function loadScript(src, type) {
    var script = document.createElement('script');
    script.src = src;
    if (type) {
        script.type = type;
    }
    script.async = false;
    document.body.appendChild(script);
}
loadScript('https://unpkg.com/react@16/umd/react.production.min.js');
loadScript('https://unpkg.com/react-dom@16/umd/react-dom.production.min.js');

// You'll need to place the REACT.JSX code above in a locally hosted file to reproduce the results: 
loadScript('react.jsx', 'text/babel');

// To toggle: rem the following line and un-rem the corresponding SCRIPT tag below
loadScript('https://unpkg.com/babel-standalone@6/babel.min.js');

</script>

<!-- To toggle: un-rem the the following SCRIPT tag and rem the last loadScript() call in the JavaScript above -->
<!--
<script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>
-->

</body>
</html>

Answer 1

babel-standalone 侦听 DOMContentLoaded 事件的触发，这导致它将任何 JSX 脚本块的转译版本附加到 HEAD。在DOM 加载结束时，如果HEAD 没有SCRIPT，则再次触发DOMContentLoaded 事件；下面是一个可以解决问题的代码块。

注意：这是针对 babel-standalone 的错误修复；如果正在使用的任何其他库也响应 DOMContentLoaded，其代码可能会运行第二次，这可能是不可取的。

document.onreadystatechange = function () {
    if (document.readyState === 'complete') {
        if (document.querySelectorAll('head script').length === 0) {
            window.dispatchEvent(new Event('DOMContentLoaded'));
        }
    }
}

因此，上面编辑的完整代码是：

<!doctype html>
<html>
<head>
    <title>Inscrutable Babel Problem</title>
    <meta charset="utf-8">
</head>
<body>
    <div>
        <p>Babel runs when the DOMContentLoaded event is fired. HELLO will display below when it works.</p>
    </div>
    <div id=app></div>
<script>
function loadScript(src, type) {
    var script = document.createElement('script');
    script.src = src;
    if (type) {
            script.type = type;
    }
    script.async = false;
    document.body.appendChild(script);
}
loadScript('https://unpkg.com/react@16/umd/react.production.min.js');
loadScript('https://unpkg.com/react-dom@16/umd/react-dom.production.min.js');
loadScript('javascript/react.jsx', 'text/babel');
loadScript('https://unpkg.com/babel-standalone@6/babel.min.js');

// Listen for completion of DOM loading; if no SCRIPT element has been added
// to the HEAD, fire the DOMContentLoaded event again:
document.onreadystatechange = function () {
    if (document.readyState === 'complete') {
        if (document.querySelectorAll('head script').length === 0) {
            window.dispatchEvent(new Event('DOMContentLoaded'));
        }
    }
}

</script>
</body>
</html>

当动态附加 Babel 时，动态附加的 JSX 不会被 Babel Standalone 转译

Dynamically appended JSX isn't transpiled by Babel Standalone when Babel is appended dynamically

javascript

reactjs

jsx

babeljs

react-dom