Question

4

Loop to remove an element in array with multiple occurrences

rated 0 times [ 9] [ 5] / answers: 1 / hits: 24522 / 11 Years ago, sun, december 22, 2013, 12:00:00

I want to remove an element in an array with multiple occurrences with a function.

var array=[hello,hello,world,1,world];



function removeItem(item){

    for(i in array){

        if(array[i]==item) array.splice(i,1);

    }

}

removeItem(world);

//Return hello,hello,1

removeItem(hello);

//Return hello,world,1,world

This loop doesn't remove the element when it repeats twice in sequence, only removes one of them.

Why?

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domeniccolti

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answered 11 Years ago piper · Accepted Answer

You have a built in function called filter that filters an array based on a predicate (a condition).

It doesn't alter the original array but returns a new filtered one.

var array=[hello,hello,world,1,world];

var filtered = array.filter(function(element) {

    return element !== hello;

}); // filtered contains no occurrences of hello

You can extract it to a function:

function without(array, what){

    return array.filter(function(element){ 

        return element !== what;

    });

}

However, the original filter seems expressive enough.

Here is a link to its documentation

Your original function has a few issues:

It iterates the array using a for... in loop which has no guarantee on the iteration order. Also, don't use it to iterate through arrays - prefer a normal for... loop or a .forEach

You're iterating an array with an off-by-one error so you're skipping on the next item since you're both removing the element and progressing the array.