带有 env preset 的 Babel 转译问题

Question

所以我最近开始学习如何使用 babel 转译器，但我发现了一个与预设的主要区别。当我使用 es2015 预设时。代码已成功转译，在我的浏览器中运行良好，但当我使用 env-preset 时，代码也已转译，但根本不起作用。

下面是我用ES6写的原代码

const jokeEl = document.getElementById('joke');
const getJoke = document.getElementById('getJoke');

getJoke.addEventListener('click', generateJoke);

generateJoke();

async function generateJoke () {

    const jokeRes = await fetch('https://icanhazdadjoke.com/', {
        headers: {
            'Accept' : 'application/json'
        }
    });

    const joke = await jokeRes.json();

    jokeEl.textContent = joke.joke;
}

这是我使用 es2015 预设时有效的代码。

'use strict';

var jokeEl = document.getElementById('joke');
var getJoke = document.getElementById('getJoke');

getJoke.addEventListener('click', generateJoke);

generateJoke();

async function generateJoke () {

    var jokeRes = await fetch('https://icanhazdadjoke.com/', {
        headers: {
            'Accept' : 'application/json'
        }
    });

    var joke = await jokeRes.json();

    jokeEl.textContent = joke.joke;
}

那么，这里是无效的代码，是使用 env 预设生成的。

"use strict";

function asyncGeneratorStep(gen, resolve, reject, _next, _throw, key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { Promise.resolve(value).then(_next, _throw); } }

function _asyncToGenerator(fn) { return function () { var self = this, args = arguments; return new Promise(function (resolve, reject) { var gen = fn.apply(self, args); function _next(value) { asyncGeneratorStep(gen, resolve, reject, _next, _throw, "next", value); } function _throw(err) { asyncGeneratorStep(gen, resolve, reject, _next, _throw, "throw", err); } _next(undefined); }); }; }

var jokeEl = document.getElementById('joke');
var getJoke = document.getElementById('getJoke');
getJoke.addEventListener('click', generateJoke);
generateJoke();

function generateJoke() {
  return _generateJoke.apply(this, arguments);
}

function _generateJoke() {
  _generateJoke = _asyncToGenerator( /*#__PURE__*/regeneratorRuntime.mark(function _callee() {
    var jokeRes, joke;
    return regeneratorRuntime.wrap(function _callee$(_context) {
      while (1) {
        switch (_context.prev = _context.next) {
          case 0:
            _context.next = 2;
            return fetch('https://icanhazdadjoke.com/', {
              headers: {
                'Accept': 'application/json'
              }
            });

          case 2:
            jokeRes = _context.sent;
            _context.next = 5;
            return jokeRes.json();

          case 5:
            joke = _context.sent;
            jokeEl.textContent = joke.joke;

          case 7:
          case "end":
            return _context.stop();
        }
      }
    }, _callee);
  }));
  return _generateJoke.apply(this, arguments);
}

Answer 1

当我不知道 babel 是如何工作的时候，我写了这个问题。我现在对它有了一些经验。我想通了。

带有 env preset 的 Babel 转译问题

Babel transpiling problem with env preset

javascript

babeljs

npm-scripts