Question

I need to know if one or more duplicates exist in a list. Is there a way to do this without travelling through the list more than once?

Thanks guys for the suggestions. I ended up using this because it was the simplest to implement:

var names = [];
var namesLen = names.length;
for (i=0; i<namesLen; i++) {
    for (x=0; x<namesLen; x++) {
        if (names[i] === names[x] && (i !== x)) {alert('dupe')}
    }
}

Answer 1

Well the usual way to do that would be to put each item in a hashmap dictionary and you could check if it was already inserted. If your list is of objects they you would have to create your own hash function on the object as you would know what makes each one unique. Check out the answer to this question.

JavaScript Hashmap Equivalent