Ive got 2 arrays, array1 and array2, that store integer values. Id like a function that takes the two arrays and returns an array with every value that is in array1 and not array2 and array2 but not array1, so:

array1(1,2,3,4,5,6)
array2(3,4,5,6,7,8)

nonIntersect(array1, array2) = array(1,2,7,8)

The order of elements is not important.

Javascripts inbuilt array functions dont seem to helpful for this. The only way i can think to perform this would be to iterate over every value in array1 against everything from array2. There has to be a better way!

Cheers for any feedback.

figured it out all on my own! if anyone can improve please let me know:

// Array.unique( strict ) - Remove duplicate values
Array.prototype.unique = function( b ) {
var a = [], i, l = this.length;
for( i=0; i<l; i++ ) {
if( a.indexOf( this[i], 0, b ) < 0 ) { a.push( this[i] ); }
}
return a;
};

//return non-intersection from self and another array
Array.prototype.nonIntersect = function nonIntersect(array2) {
//create a copy, dont work on original
array1 = this;
var differenceArray = new Array();
array1 = array1.unique();
array1.sort();
array2 = array2.unique();
array2.sort();

for (i=0; i<array1.length; i++) {
//if array2 is empty everything in array1 is unique, so add it to differenceArray and quit
if (array2.length == 0) {
differenceArray = array1.concat(differenceArray);
break;
}
if (array1[i] < array2[0]) {
differenceArray[differenceArray.length] = array1[i];
continue;
}
if (array1[i] == array2[0]) {
array2.shift();
continue;
}
if (array1[i] > array2[0]) {
differenceArray[differenceArray.length] = array2[0];
array2.shift();
//need to check array[i] again so remove the effect of incrementation here:
i--;
continue;
}
}
//if there are any elements remaining in array2 they must not be in array1 so add to differenceArray
if (array2.length > 0) {
differenceArray = array2.concat(differenceArray);
}
return (differenceArray.sort());
};

This may be what you are looking for:

        function arrayInverse(all, subset) {
            if (subset.length == 0){
                return all;
            }
            
            var inverse = new Array();
            var found = false;
            
            for (x in all){
                found = false;
                for (var y=0; y<subset.length; y++){
                    if (subset[y]==all[x]){
                        found = true;
                        y=subset.length;
                    }
                }
                if (found == false){
                    inverse.push(all[x]);
                }
            }
            return inverse;
        }