Littlest things

一道关于JavaScript柯里化的面试题

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题目

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编写一个函数
console.log(mul(1)(2)(3))  //6    
console.log(mul(2)(3)(4))  //24

解法

优解

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// es6
   const mul = (x) => {
    let sum = x
    let curried = (y) => {
        sum = sum * y
        return curried
    }
    curried.toString = () => sum
    return curried
   }
    console.log(mul(1)) //1
    console.log(mul(1)(2))//2
    console.log(mul(1)(2)(3))//6
    console.log(mul(1)(2)(3)(4))//24
    ...
    
   // es5
 function mul(x){
  var sum = x
  var curried = function(y){
    sum = sum * y
    return curried
  }
  curried.toString=function(){
    return sum 
  }
  return curried
}
    console.log(mul(1)) //1
    console.log(mul(1)(2))//2
    console.log(mul(1)(2)(3))//6
    console.log(mul(1)(2)(3)(4))//24
    ...

这种解法主要用的是闭包，然后将函数作为返回值，然后重写curried的toString

最简单的解法

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//es6
const mul = (x) =>(y) =>(z) => x*y*z
console.log(mul(1)(2)(3))
//es5
function mul(x){
    return function(y){
        return function(z){
            return x*y*z
        }
    }
}
console.log(mul(1)(2)(3))

这种解法就是完全,就是使用柯里化了