Javascript返回具有原始值的数组索引的引用

Question

I want to return a reference to to the content of an array at index x in order to be able to change the content of the array using the returned index afterwards. Here is an example of what I mean:

let testArr = [1,2,3]
const someFunct = arr => {
    ...
    return {reference to arr[0], aka 1}
}
someFunct(testArr) = 0;

//should log [0,2,3]
console.log(testArr);

someFunct(testArr) should behave like arr[0] in this case.
The content of the array could be anything.

Answer 1

i dont think the exact implementation you are trying to achieve is possible in JavaScript.

https://medium.com/@naveenkarippai/learning-how-references-work-in-javascript-a066a4e15600

something similar:

const testArr = [1,2,3]
const changeArray = (array, index, newValue) => {
    array[index] = newValue
    return array
}

changeArray(testArr, 0, 0) // evaluates to [0,2,3]

Answer 2

I want to return a reference …

This is not possible, JavaScript doesn't have references as returnable values. The someFunct(testArr) = 0; syntax you are imagining is invalid.

Instead, take the new value as an argument:

function someFunct(arr, val) {
    …
    arr[0] = val;
}
someFunct(testArr, 0);

or return an object with a method that does the assigning:

function someFunct(arr) {
    …
    return {
        set(v) {
            arr[0] = v;
        }
    };
}
someFunct(testArr) = 0;

Answer 3

Try this:

  function arrayWrapper(arr, index, newVal) { let returnVal; if(newVal) { arr[index] = newVal; returnVal = arr; } else { const obj = { ...arr }; returnVal = obj[index]; } return returnVal; }; console.log(arrayWrapper([1,2,3,4,5,6,7,8,9], 5)); /// to get value at index console.log(arrayWrapper([1,2,3,4,5,6,7,8,9], 5, 'text')); // to set value on index 

You can use the above method to get as well as set elements to your array. The nature of operation depends on the third parameter.

Hope this helps :)