Array.push() and unique items

Question

I have a simple case of pushing unique values into array. It looks like this:

  this.items = [];

  add(item) {
    if(this.items.indexOf(item) > -1) {
           


        

Answer 1

Your logic is saying, "if this item exists already, then add it." It should be the opposite of that.

Change it to...

if (this.items.indexOf(item) == -1) {
    this.items.push(item);
}