console.log(sum(1, 2, 3, 4, 5).valueOf()) // => 15console.log(sum(1, 2)(3, 4)(5).valueOf()) // => 15console.log(sum(1, 2)(3)(4)(5).valueOf()) // => 15console.log(sum(1)(2)(3)(4)(5).valueOf()) // => 15复制代码

/** * @author shao * @date 2018/03/05 * @project test */let sum = function () {    let prevSum = [...arguments].reduce((a, b) => a + b)    let result = function () {      return sum(...([...arguments].concat(prevSum)))    }    result.valueOf = function () {      return prevSum    }    return result  }console.log(sum(1, 2, 3, 4, 5).valueOf()) // => 15console.log(sum(1, 2)(3, 4)(5).valueOf()) // => 15console.log(sum(1, 2)(3)(4)(5).valueOf()) // => 15console.log(sum(1)(2)(3)(4)(5).valueOf()) // => 15复制代码