Babel 替换条件确定的 if 判断或条件表达式代码

if (1 > 2) {
    console.log('a');
}
else {
    console.log('b');
}

if (0) {
    console.log('c');
}

if (1) {
    console.log('111');
}

if (2) {
    let cc = 'cc';
    console.log('d -- ' + cc);
}

if (2 > 3) {
    console.log('f');
}
else if (5 % 2 === 0) {
    console.log('g');
}
else if (!![]) {
    console.log('h');
}
else {
    console.log('i')
}

var j = 2 >= 3 ? 'j11' : 'j22';
console.log(![] ? '---' : '~~~');

console.log('b');

if (0) {
  console.log('c');
}

console.log('111');

if (2) {
  let cc = 'cc';
  console.log('d -- ' + cc);
}

console.log('h');
var j = 'j22';
console.log('~~~');

// decrypt.js
const fs = require('fs');
var util = require('util');
const parser = require('@babel/parser');
const traverse = require('@babel/traverse').default;
const types = require('@babel/types');
const generator = require('@babel/generator').default;

// 程序启动时间
var time_start = new Date().getTime()
// 读取文件
process.argv.length > 2 ? encode_file = process.argv[2] : encode_file = 'encode.js';
process.argv.length > 3 ? decode_file = process.argv[3] : decode_file = 'decode.js';

let jscode = fs.readFileSync(encode_file, { encoding: 'utf-8' });
console.log(util.format('Reading the file [%s] is complete.', encode_file))
// 转换为 ast 树
let ast = parser.parse(jscode);

const visitor =
{
    IfStatement(path) {
        let consequent_path = path.get('consequent');
        let alternate_path = path.get('alternate');
        let test_path = path.get('test');
        if (!types.isBlockStatement(consequent_path)) {
            consequent_path.replaceWith(types.blockStatement([consequent_path]));
        }

        if (alternate_path && !types.isBlockStatement(alternate_path)) {
            alternate_path.replaceWith(types.blockStatement([alternate_path]));
        }

        let replace_path;
        let { confident, value } = test_path.evaluate();
        if (!confident) {
            return;
        }
        if (value) {
            replace_path = consequent_path;
        }
        else {
            if (!alternate_path) {
                path.remove();
                path.scope.crawl();
                return
            }
            replace_path = alternate_path;

        }
        for (let statement of replace_path.node.body) {
            if (types.isVariableDeclaration(statement) && statement.kind !== 'var') {
                return;
            }
        }
        path.replaceWithMultiple(replace_path.node.body);
        path.scope.crawl();
    },
    ConditionalExpression(path) {
        let consequent_path = path.get('consequent');
        let alternate_path = path.get('alternate');
        let test_path = path.get('test');

        let { confident, value } = test_path.evaluate();
        if (!confident) {
            return;
        }

        if (value) {
            path.replaceWith(consequent_path);
        }
        else {
            path.replaceWith(alternate_path);
        }
        path.scope.crawl();
    }
}

//调用插件，处理待处理 js ast 树
traverse(ast, visitor);
console.log('AST traverse completed.')

// 生成处理后的 js
let { code } = generator(ast);
console.log('AST generator completed.')
fs.writeFile(decode_file, code, (err) => { });
console.log(util.format('The javascript code in [%s] has been processed.', encode_file))
console.log(util.format('The processing result has been saved to [%s].', decode_file))
// 程序结束时间
var time_end = new Date().getTime()
console.log(util.format('The program runs to completion, time-consuming: %s s', (time_end - time_start) / 1000))