徒手写一个es6代码库

mkdir demo
cd demo
npm init
npm install -g babel
npm install -g babel-cli
npm install --save-dev babel-preset-es2015-node5

在项目目录创建两个文件夹 functional-playground 和lib

mkdir functional-playground
mkdir lib

在lib目录下创建文件 es6-functional.js

const forEach = (array, fn) => {
  let i;
  for (i = 0; i < array.length; i++)
    fn(array[i])
}

export default forEach

在functional-playground目录下创建文件play.js

import forEach from '../lib/es6-functional'

var array = [1, 2, 3]
forEach(array, (data) => console.log(data))

执行命令

babel-node functional-playground/play.js --presets es2015-node5

执行结果如下

也可以将上述脚本写到package.json中

执行 npm run playground 命令可以查看到一样的结果

在es6-functional.js中定义更多的抽象函数

const forEach = (array, fn) => {
  let i;
  for (i = 0; i < array.length; i++)
    fn(array[i])
}

const forEachObject = (obj, fn) => {
  for (var property in obj) {
    if (obj.hasOwnProperty(property)) {
      fn(property, obj[property])
    }
  }
}

const unless = (predicate, fn) => {
  if (!predicate)
    fn()
}

export {
  forEach,
  forEachObject,
  unless
}

在 play.js 调用

import {
  forEach,
  forEachObject,
  unless
} from '../lib/es6-functional'

var array = [1, 2, 3]
forEach(array, (data) => console.log(data))

let object = {
  a: 1,
  b: 2
}
forEachObject(object, (k, v) => console.log(k + ":" + v))

forEach([1, 2, 3, 4, 5, 6, 7], (number) => {
  unless((number % 2), () => {
    console.log(number, " is even")
  })
})

执行 npm run playground 命令查看结果