如何创建反向数组 function？

Question

I am trying to write a function, reverseArray(), that takes in an array as an argument and returns a new array with the elements in the reverse order ( without using the built-in method ).

Can someone help me to see what I'm doing wrong here? It returns 1 when I ran the code below.

 const reverseArray=array=> { let newArray=[]; for (let i=array.length-1; i>=0; i--){ return newArray.push(array[i])} }; const array = ['sense.','make', 'all', 'will', 'This']; console.log(reverseArray(array));

Answer 1

You're returning the results of Array.push() on the first instance of the loop. According to MDN, Array.push() returns:

The new length property of the object upon which the method was called.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push

So it's pushing one element to the array, and returning the length of the array (1).

Instead, add all the elements to the array in the for loop, then return the array itself:

 const reverseArray = arr => { let newArr=[] for (let i=arr.length-1; i>=0; i--){ newArr.push(arr[i]) } return newArr } const arr = ['sense.','make', 'all', 'will', 'This'] console.log(reverseArray(arr))