ReactJS.NET中函数无法触发，如何在render中调用箭头函数？

Hey there! Let's break down why your test arrow function isn't triggering in the CommentBox component's render method, and how to fix it properly.

Why Your Current Approaches Aren't Working #

• <test />: This syntax tells React to treat test as a React component, not a regular function. Since test isn't defined as a component (it doesn't follow React's component rules, like starting with an uppercase letter or returning valid JSX), this won't execute the function at all.
• {test}: Here you're just passing the function reference to JSX, not actually calling it. React will convert the function object to a string and display it (like () => { ... }) instead of running the code inside.

The Correct Way to Call the Function #

To execute your test function inside render, you need to call it explicitly with parentheses: {test()}. But there's one more tweak needed—your function returns an HTML string right now, which React will render as plain text by default. Let's fix that too.

Option 1: Return JSX Instead of a String (Recommended)

Rewrite your test function to return a JSX element instead of an HTML string—this is the standard, safe React approach:

let test = () => {
  console.log('called!');
  return <p>Testing</p>; // No quotes, just native JSX
}

var CommentBox = React.createClass({
  render: function () {
    return (
      <div className="commentBox">
        Hello, world! I am a CommentBox.
        {test()} {/* This executes the function and renders the <p> element */}
      </div>
    );
  }
});

ReactDOM.render(
  <CommentBox />,
  document.getElementById('root') // Make sure your HTML has a root element with this ID
);

Option 2: Use dangerouslySetInnerHTML (For HTML Strings)

If you have to return an HTML string for some reason, you can use React's dangerouslySetInnerHTML prop to render it as actual HTML. Important: Only use this if you fully trust the source of the HTML, as it can expose your app to XSS vulnerabilities.

let test = () => {
  console.log('called!');
  return "<p>Testing</p>";
}

var CommentBox = React.createClass({
  render: function () {
    return (
      <div className="commentBox">
        Hello, world! I am a CommentBox.
        <div dangerouslySetInnerHTML={{ __html: test() }} />
      </div>
    );
  }
});

Quick Side Note #

If you ever build a custom React component later on, remember that React requires component names to start with an uppercase letter (like Test instead of test). This helps React tell the difference between built-in HTML elements and your custom components.

内容的提问来源于stack exchange，提问作者Lars Holdgaard