Example of extending the Array contains method in JavaScript, arraycontains

Example of extending the Array contains method in JavaScript, arraycontains

The Array in javascript does not have the contains method, which is sometimes inconvenient. The contains method is implemented very easily:
Copy codeThe Code is as follows:
Function contains (a, obj ){
Var I = a. length;
While (I --){
If (a [I] = obj ){
Return true;
}
}
Return false;
}

Of course, we can also extend the Array class, as shown in the following js
Copy codeThe Code is as follows:
Array. prototype. contains = function (obj ){
Var I = this. length;
While (I --){
If (this [I] === obj ){
Return true;
}
}
Return false;
}

In this way, you can easily use the contains method:
Copy codeThe Code is as follows:
Alert ([1, 2, 3]. contains (2); // => true
Alert ([1, 2, 3]. contains ('2'); // => false