findSumPairs.js

function findSumPairs(arr, sum) {
	'use strict';
    var
        i = 0,
        j = 0,
        isum,
        imatch,
        out = [],
        larr;

    larr = arr.slice(0); // shallow copy (just in case)

    for ( i = 0; i < larr.length; i++ ) {

    	for ( j = 0; j < larr.length; j++ ) {

    		if ( i !== j ) {

	    		isum = larr[i] + larr[j];
	    		if ( isum === sum ) {

	    			imatch = [larr[i], larr[j]];
	    			out.push(imatch);
	    			larr.splice(i, 1);
	    			larr.splice(j, 1);
	    			break;
	    		}
    		}
    	}
    }

    return out;
}