Removing array elements by index

Question

arr1 is an array of integers. arr2 contains the list of indexes of elements that I wish to remove from arr1.

So this my JS function:

function deletion()
{
        var arr3=[];
        var arr1= [2,3,4,5,6,7,8,11,22];
        console.log(arr1);
        var arr2 = [4,0,1];

        for(var i=0;i<arr2.length;i++)
    {
    arr3.push(arr1[arr2[i]]);
    }
    for(var j=0;j<arr3.length;j++)
    {
     arr1.splice(arr1.indexOf(arr3[j]),1);
    }
        console.log(arr1,"array1");
}

This works fine but now the requirement is : I need to use more efficient way . arr3 should not be used i.e I don't want to use another new array and push elements into it and then loop through it.I want this to be achieved without using new array.

Is there a way to achieve this??and no library should be used,this must be done through Java Script only.

Apologies if the question is ridiculous.. This is for an assignment that I must complete.

if you simply want to avoid use of a third array, then sort arr2 in descending order and then splice arr1 directly. — Pranav Gupta
– Pranav Gupta, Commented Nov 1, 2013 at 10:06

Pranav Gupta · Accepted Answer · 2013-11-01 10:15:07Z

1

var arr1= [2,3,4,5,6,7,8,11,22];
var arr2 = [4,0,1];
arr2 = arr2.sort().reverse();
for(var i = 0; i < arr2.length; i++){
    arr1.splice(arr2[i],1);
}
console.log(arr1);

answered Nov 1, 2013 at 10:15

Pranav Gupta

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Comments

afei · Accepted Answer · 2013-11-01 10:19:18Z

1

function deletion()
{
    var arr1= [2,3,4,5,6,7,8,11,22];
    console.log(arr1);
    var arr2 = [4,0,1];
    arr2 .sort(function(a,b){return a>b?-1:1});
    for(var i=0;i<arr2.length;i++)
    {
       arr1.splice(arr2[i],1);
    }
    console.log(arr1,"array1");
}

answered Nov 1, 2013 at 10:19

afei

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Comments

Chris Pickford · Accepted Answer · 2013-11-01 10:09:06Z

0

You can use Array.splice to this effect, it may not be appropriate in this form due to the double loop complexity but you get the idea...

var arr1= [2,1,3,4,5,6,7,8,11,22],
    arr2 = [4,0,1];

for (var i in arr1) {
    for (var j in arr2) {
        if (arr1[i] == arr2[j])
            arr1.splice(i, 1);
    } 
}

answered Nov 1, 2013 at 10:09

Chris Pickford

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