How To implement unshift method in Javascript

Question

i need make function like this:

Function add(arr,...newVal){

}

array = [1,2,3];
add(array,0)
console.log(array);        //i need here to print [0,1,2,3]

iam make function as push like that:

Function add(arr,...newVal){
for(var i=0; i<arr.length; i++){
arr[arr.length]=newVal[i];
}return arr.length;
}

array = [1,2,3];
add(array,4)
console.log(array);        // here to print [1,2,3,4]

why don't use Array.unshift() ? developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… why don't use Array.push() ? developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… — Romain TAILLANDIER
– Romain TAILLANDIER, Commented Dec 6, 2022 at 10:35

Romain TAILLANDIER · Accepted Answer · 2022-12-06 10:33:44Z

2

const unshift = (arr, ...newVal) => {
    let i= arr.length + newVal.length -1;
    for( i ; i >= newVal.length; i--) {
        arr[i] = arr[i - newVal.length ];
    }

    for(i; i >= 0; i--) {
        arr[i] = newVal[i];
    }
    return arr;
}

answered Dec 6, 2022 at 10:33

Romain TAILLANDIER

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Comments

Vardhan · Accepted Answer · 2022-12-06 09:12:07Z

0

Try this:

const unshift = (arr, newVal) => {
    for(let i = arr.length; i > 0; i--) {
        arr[i] = arr[i - 1];
    }
    arr[0] = newVal;
    return arr;
}

answered Dec 6, 2022 at 9:12

Vardhan

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1 Comment

Ahmed Mahrous Over a year ago

but here sir i cant add more than one items

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