Question

77

Get every nth item in array

rated 0 times [ 81] [ 4] / answers: 1 / hits: 24683 / 14 Years ago, wed, january 26, 2011, 12:00:00

I have an array of HTML elements. I'm checking whether a previous object in the array exists like this:

var boxes = $('.box'); // creating the array



boxes.each(function(i){ // going through the array

    var prevBox = i>0?$(boxes[i-1]):false; // check whether a previous box exists

    if (prevBox) { } // do something

    else { } // do something else

});

This works well. But I would also need to check the existence of every fourth object (box) in the array, or more precisely whether an object three objects before the current one exists.

This doesn't work:

var prevBox = i>0?$(boxes[i-4]):false;

I believe using jQuery.grep() and checking if (i % 4) == 0 might be the answer, but with my limited knowledge of Javascript, I don't know how to apply it to what I have now.

Anyone can help? Thanks!

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jonmicahm

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4 Years ago

answered 14 Years ago byrondonavanc · Accepted Answer

~~You can use the modulus operator in the loop to see if you are on a fourth interval.~~

Question was clarified.

var boxes = $('.box'); // creating the array



boxes.each(function(i){

    if( i >= 3 ) {

        var prevBox = boxes.eq( i - 3 );

        var pos = prevBox.position();

        var top = pos.top;

    }

});