js 函数实现

[EchoZhaoH]

currying

function currying() {
    const arr = Array.from(arguments) 
    const fn = arr.shift()
    let rest = arr
    if (rest.length === fn.length) {
        return fn.apply(this, rest)
    }
    return function loop() {
        const args = rest.concat(...Array.from(arguments))
        if (args.length === fn.length) {
           return fn.apply(this, args)
        } else {
               return loop.apply(this, args)
        }
    }
}

new 的实现过程

function NewInstance(parent) {
    const obj = Object.create({})
    obj.__proto__ = Object.create(parent.prototype)
    const result = parent.apply(obj)
    return result instanceof Object ? result : obj 
}

instanceof 实现过程

function instanceofClone(child, parent) {
    let a = child.__proto__
    while(a) {
        if (a === parent.prototype) return true
         a = a.__proto__
    }
    return false
}