Diff of Two Arrays -- JavaScript -- Free Code Camp

**Diff of Two Arrays** -- Finding the symmetric difference or the difference between two arrays. This function uses our good friends `filter()`, `concat()`, `slice()`, and `indexOf()`.

[elonwu]

The following works for me:

function diffArray(arr1, arr2) {
var copy1 = arr1;
var copy2 = arr2;
for(i=0; i<copy1.length; i++){
for(j=0; j<copy2.length; j++){
if(copy1[i] == copy2[j]){
copy1.splice(i, 1);
copy2.splice(j, 1);
i-=1;
j-=1;
}
}
}
var new_Arr = copy1.concat(copy2);
return new_Arr;
}

[supersteve]

Thanks for this Stephen. I couldn't work out how to do this challenge using all the methods that FreeCodeCamp suggested. However, thankfully I did complete the challenge using the include method that you introduced in a previous video:

function diffArray(arr1, arr2) {
var firstArr = arr1.filter(function(letter) {
return !arr2.includes(letter);
});
var secondArr = arr2.filter(function(letter) {
return !arr1.includes(letter);
});
return firstArr.concat(secondArr);
}

[young]

If the first array contains a duplicate value, and that value is not present in the second array, it will still filter it out.

[glendonphilippbaculio]

your videos are amazing what books do you suggest? what are the best resources to learn javascript?