自定义 babel 插件 - 无法遍历（访问）JSXElement

Question

I am trying to write a custom babel transform plugin. When see the AST for a React component in astxplorer.net , I see JSXElement in the tree as a node.

But when I try to log the path for the visitor JSXElement , nothing logs to the console.

React component

const HelloWorld = () => <span>Hello World</span>

Code to transform the component and log JSXElement while visiting

transform.test.js

const { code, ast } = transformSync(HelloWorld, {
    ast: true,
    plugins: [
      function myOwnPlugin() {
        return {
          visitor: {
            JSXElement(path) {
              // nothing logs to the console
              console.log("Visiting: " + path);
            }
          }
        };
      },
    ]
  });

If it helps, I have the transform.test.js inside an ejected create-react-app project. CRA comes with built-in preset react-app .

"babel": {
    "presets": [
      "react-app"
    ]
  }

I run the test with the command jest transform.test.js and I have babel-jest transform applied by default in CRA jest setup.

Answer 1

I think you're passing the component to Babel instead of the code for the component, you need to transform the actual code as a string, for example, something like this:

const { code, ast } = transformSync(`const HelloWorld = () => <span>Hello World</span>`, {
    ast: true,
    plugins: [
      function myOwnPlugin() {
        return {
          visitor: {
            JSXElement(path) {
              // nothing logs to the console
              console.log("Visiting: " + path);
            }
          }
        };
      },
    ]
  });```