Why for loop returning last value alone instead of all other values in javascript

Question

I have function something below,

function test(){
    const obj = {}
    const arr = []

    for(let i = 0; i < 100; i++) {
        obj.i = i
        arr.push(obj)
    }

    return arr
} 

const res = test();
console.log(res);

which returns

[{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99},{"i":99}]

but why it not return

[{"i":0},{"i":1},...,{"i":99}]

any reason.

Because the you push the reference to the initial object, not a new object. — 0stone0, May 22 '23 at 10:34
Because you keep referring to the same object. You can fix it by creating the object inside the loop. — Kokodoko, May 22 '23 at 10:34

score 2 · Accepted Answer · answered May 22 '23 at 10:38

You are replacing the value each time it is looping.Do like this

function test(){
     const arr = []
     for(let i = 0; i < 100; i++) {
         const obj = {}
        obj.i = i
        arr.push(obj)
     }

    return arr
} 

const res = test();
console.log(res);

Why for loop returning last value alone instead of all other values in javascript

1 Answers1