Check item is already exists in an array using JS

const onlyArr = ["1","3","4","5"]
const isExist = onlyArr.indexOf("3") !== -1
console.log('isExist',isExist)

Output=> true

Comments

[Jon Randy 🎖️]

You can shorten this to:

const isExist = ~onlyArr.indexOf("3")

Or, using something much more readable:

const isExist = onlyArr.includes("3")

[Deveesh Shetty]

The first time I saw the ~ (Bitwise NOT) operator being used
I tried it and it gives a negative number if the element is present and 0 if it is not.

So why not use !! in front of it which will give the answer in a boolean

const arr = ["A", "B", "C", "D"]
!!~arr.indexOf("F") // false
!!~arr.indexOf("B") // true

Rip readability tho... but yeah the second option is preferable using .includes() and the one which OP mentioned, I was just messing around with the ~ operator

[Jon Randy 🎖️]

A boolean is unnecessary since values have truthiness and falsiness - -1 will become a falsy value (0), everything else will be truthy (negative numbers). Converting manually to a Boolean is inefficient and unnecessary

[Deveesh Shetty]

Oh yeah that's true, didn't think of that way.

Thank you!