ast 删除未使用的变量

 

 

const fs = require('fs');
const {parse} = require("@babel/parser");
const traverse = require("@babel/traverse").default;
const t = require("@babel/types");

const generator = require("@babel/generator").default;



let jscode = `var s = 92;
            b = Z(1324801, 92);`;

let ast = parse(jscode);

const visitor = {
    VariableDeclarator(path)
    {//还原var、let、const 定义的变量
        const {id,init} = path.node;

        if (!t.isLiteral(init)) return;//只处理字面量       
        
        const binding = path.scope.getBinding(id.name);
      
        if (!binding || binding.constantViolations.length > 0)
        {//如果该变量的值被修改则不能处理
            return;
        }

        for (const refer_path of binding.referencePaths) 
        {
            refer_path.replaceWith(init);
        }
        path.remove();
    },
}

traverse(ast, visitor);

let {code} = generator(ast);

console.log(code);

//--------------------

b = Z(1324801, 92);