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

so not sure if this answers your question but the indexOf the items you are adding keep returning -1. Not to familiar with js but it appears the items do that because they are not in the array yet. I made a jsfiddle of a little modified code for you.

this.items = [];

add(1);
add(2);
add(3);

document.write("added items to array");
document.write("
");
function  add(item) {
        //document.write(this.items.indexOf(item));
    if(this.items.indexOf(item) <= -1) {

      this.items.push(item);
      //document.write("Hello World!");
    }
}

document.write("array is : " + this.items);

https://jsfiddle.net/jmpalmisano/Lnommkbw/2/