JavaScript and Python: Check if Item is in Array (or List)

JavaScript

We can use indexOf method to do that.

let a = ["one", 2, "tree", "floor", 5, "socks"]; console.log(a.indexOf("floor")); // 3 console.log(a.indexOf(4)); // -1 // (Not in the array)

Using indexOf, we'll expect integer output. Returned value -1 (negative one) is to tell that the item isn't present in the array.

In latest version of ECMA (latest browsers), we can use includes method.

let a = ["one", 2, "tree", "floor", 5, "socks"]; console.log(a.includes("floor")); // true console.log(a.includes(4)); // false

Using includes, we'll expect boolean output (true / false).

---

Python

Well, the phrase itself, "check if item in list", then we can use in operator to do that.

list = ["one", 2, "tree", "floor", 5, "socks"] print 1 in list # False print "tree" in list # True

Using that method, we'll expect boolean output (True / False).