babel 简单插件

package.json

{
  "name": "babel-test",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "devDependencies": {
    "@babel/core": "^7.13.10"
  }
}

要编译的原代码fun.js

const c = '';

babel 插件 plugin.js

module.exports = function(babel) {
    const t = babel.types;
    return {
        visitor: {
            VariableDeclarator(path, state) {
                // 使用a替换变量名c
                if(path.node.id.name == 'c'){
                    path.node.id = t.identifier('a')
                }
                // 使用["any"]替换字符串字面量
                if (t.isStringLiteral(path.node.init)) {
                    const element = t.stringLiteral('any');
                    path.node.init = t.arrayExpression([element]);
                }
            }
        }
    }
}

编译文件index.js

const babel = require('@babel/core');
const pluginFunc = require('./plugin');
const configItem = babel.createConfigItem(pluginFunc);
const ret = babel.transformFileSync('fun.js', { plugins: [configItem], ast: true});
console.log(ret.code);

输出代码

const a = ["any"];

将code转化为AST节点在线查看器 AST explorer

babel.types API