No.815 实现 add(1)(2)(3)

考点：函数柯里化

函数柯里化概念： 柯里化（Currying）是把接受多个参数的函数转变为接受一个单一参数的函数，并且返回接受余下的参数且返回结果的新函数的技术。

粗暴版本

function add (a) {
    return function (b) {
        return function (c) {
            return a + b + c;
        }
    }
}
console.log(add(1)(2)(3)); // 6

柯里化解决方案

参数长度固定

const curry = (fn) =>
(judge = (...args) =>
    args.length === fn.length
    ? fn(...args)
    : (...arg) => judge(...args, ...arg));
const add = (a, b, c) => a + b + c;
const curryAdd = curry(add);
console.log(curryAdd(1)(2)(3)); // 6
console.log(curryAdd(1, 2)(3)); // 6
console.log(curryAdd(1)(2, 3)); // 6

参数长度不固定

function add (...args) {
    //求和
    return args.reduce((a, b) => a + b)
}

function currying (fn) {
    let args = []
    return function temp (...newArgs) {
        if (newArgs.length) {
            args = [
                ...args,
                ...newArgs
            ]
            return temp
        } else {
            let val = fn.apply(this, args)
            args = [] //保证再次调用时清空
            return val
        }
    }
}

let addCurry = currying(add)
console.log(addCurry(1)(2)(3)(4, 5)())  //15
console.log(addCurry(1)(2)(3, 4, 5)())  //15
console.log(addCurry(1)(2, 3, 4, 5)())  //15

以上解析来自 ---》 查看更详细解析--》 https://github.com/lgwebdream/FE-Interview/issues/21