常量计算

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

// 将js代码转换成AST
// const { parse } = require("@babel/parser");
// 用来遍历AST中的节点
// const traverse = require("@babel/traverse").default;
// AST转换成js
const generator = require("@babel/generator").default;
// 用来判断节点类型和生成新的节点
const types = require("@babel/types");


const jscode = `

var a = !![],b = 'Hello ' + 'world' + '!',c = 2 + 3 * 50,d = Math.abs(-200) % 19,e = true ? 123:456;



`;
let ast = parser.parse(jscode);


const constantFold = 
{
      "BinaryExpression|UnaryExpression|ConditionalExpression|CallExpression|MemberExpression|SequenceExpression"(path)
    {
        if(path.isUnaryExpression({operator:"-"}) || path.isUnaryExpression({operator:"void"}))
        {
            return;
        }
        const {confident,value} = path.evaluate();
        if (value == "Infinity" || !confident) return;
        path.replaceInline(types.valueToNode(value));
    },
}

traverse(ast, constantFold);


let { code } = generator(ast);

console.log(code);

标签：traverse,const,常量,babel,require,parser,计算,path
来源： https://www.cnblogs.com/angdh/p/15758042.html