check collision between certain divs?

Question

Anyone know how to check for collision between certain divs? At the moment I'm using getBoundingClientRect(), but it checks for every div:

if (this.getBoundingClientRect()) {
    animateContinue = 1;
}

How would I go about checking specific ones? Using this for loop I can get the IDs of the divs I want to check.

for (var x = 1; x <= noOfBoxArt; x++) {
    console.log('#boxArt'+x);
}

Answer 1

Okay. Ended up using a modified version of this duplicate. The function which does the work is:

var overlaps = (function () {
    function getPositions( elem ) {
        var pos, width, height;
        pos = $( elem ).position();
        width = $( elem ).width() / 2;
        height = $( elem ).height();
        return [ [ pos.left, pos.left + width ], [ pos.top, pos.top + height ] ];
    }

    function comparePositions( p1, p2 ) {
        var r1, r2;
        r1 = p1[0] < p2[0] ? p1 : p2;
        r2 = p1[0] < p2[0] ? p2 : p1;
        return r1[1] > r2[0] || r1[0] === r2[0];
    }

    return function ( a, b ) {
        var pos1 = getPositions( a ),
            pos2 = getPositions( b );
        return comparePositions( pos1[0], pos2[0] ) && comparePositions( pos1[1], pos2[1] );
    };
})();

and is called by using overlaps( div1, div2 ); (returns true or false).

Answer 2

Pure JS version

var overlaps = (function () {
    function getPositions( elem ) {
        var width = parseFloat(getComputedStyle(elem, null).width.replace("px", ""));
        var height = parseFloat(getComputedStyle(elem, null).height.replace("px", ""));
        return [ [ elem.offsetLeft, elem.offsetLeft + width ], [ elem.offsetTop, elem.offsetTop + height ] ];
    }

    function comparePositions( p1, p2 ) {
        var r1 = p1[0] < p2[0] ? p1 : p2;
        var r2 = p1[0] < p2[0] ? p2 : p1;
        return r1[1] > r2[0] || r1[0] === r2[0];
    }

    return function ( a, b ) {
        var pos1 = getPositions( a ),
            pos2 = getPositions( b );
        return comparePositions( pos1[0], pos2[0] ) && comparePositions( pos1[1], pos2[1] );
    };
})();