Creating a button based on values in array JS

Question

So basically, I made an empty array with JS, which is filled in dynamically based on user choice. Now, I would like a button to appear based on weather or not a value is stored inside the array. And I can't seem to do that, even though a required value is inside the array. Both array and button creation are the part of the same script, if such information makes difference. My code is something like this:

array = [];
//somewhere along the way it get's filled up...
//...
if (array.indexOf("anItem") == true){
var btn = document.createElement('button');
btn.innerHTML = "Text";
btn.setAttribute('id', 'button2');
paragra.appendChild(btn);
}

What am I doing wrong and is there hope for me?

from this: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… indexOf doesnt return a boolean, but a -1 if false. that might be the first issue — Andriy Lysak
– Andriy Lysak, Commented Nov 25, 2015 at 23:27

Keith · Accepted Answer · 2015-11-25 23:30:57Z

3

Change the line from

if (array.indexOf("anItem") == true){

to

if (array.indexOf("anItem") != -1){

and let us know if there are any other problems. indexOf() returns the position of your value within the array, or -1 if it can't find it.

answered Nov 25, 2015 at 23:30

Keith

9946 silver badges9 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

I hate JS Over a year ago

I tested it only a bit, but it seems to fix my issue. It didn't occur to me that the return value of indexOf is it not true/false. I will test it further later on. Thank you for your help!

Arjun · Accepted Answer · 2015-11-25 23:41:01Z

1

This will work :-

array = [];

if(array.indexOf("anItem") != -1){
  //Item available
}else{
  // Item not available
}

indexOf returns the index of an Item in an array and if the Item is not found, it returns -1. The above code checks whether the indexOf("anItem") returns -1 or not.

Edit

BTW, a method named includes() is a part of ECMAScript 7. See this. However, ECMAScript 7 lacks browser support.

edited Nov 25, 2015 at 23:41

answered Nov 25, 2015 at 23:32

Arjun

1,4051 gold badge13 silver badges28 bronze badges

1 Comment

I hate JS Over a year ago

Thank you for you comment, it was very helpful. I will check out includes() method you mentioned, despite it's inflexibility.

Collectives™ on Stack Overflow

Creating a button based on values in array JS

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related