Check Element not in array in java script? [duplicate]

Question

Hi I am New to JS i trying below code

a=[0,1,3]
if (2 in a){ console.log(a)}

in above code i am checking element is available are not. but in above case 2 is not in array but condition show true why?

i know we can check condition like this a.includes(2) why in above case showing true?

Thanks Advance.

"The in operator returns true if the specified property is in the specified object or its prototype chain.". Here, the key "2" is a property of this Array (it's the index of the value "3") — blex
– blex, Commented Mar 30, 2020 at 9:49
0xc14m1z's answer is correct - what you need to use is a.indexOf(2) !== -1 for checking if 2 is in a. be careful using .includes(), it's not supported in IE — andy mccullough
– andy mccullough, Commented Mar 30, 2020 at 9:51

0xc14m1z · Accepted Answer · 2020-03-30 09:49:27Z

5

Becase the in operator checks whether a property is defined in an object.

The array indexes are the "properties" of the array objects, thus, the 2 property is the index 2, which contains the value 3.

answered Mar 30, 2020 at 9:49

0xc14m1z

3,7252 gold badges16 silver badges24 bronze badges

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

1 Answer 1