Compile js extension method to determine whether an array contains a certain element _ javascript skills

To determine whether a set Contains an element, we can use the js prototype extension to encapsulate our own Contains method. The specific ideas and implementation are as follows, if you are interested, you can refer to the C # syntax to determine whether the set Contains an element. You can use the Contains method. But how can you solve similar problems in javascript, js does not have the Contains method.
We can use the js prototype extension to encapsulate our own Contains method.

Js Code:

The Code is as follows: