How to add prototype in string object using javascript

Question

I want to add prototype function in string object. I working with it but it is not uppercase the string value. Fiddle

String.prototype.myUcase=function()
{
 return this.toUpperCase();
}

You don't assign the return value of myUcase to a variable, you simply ignore it. toUpperCase doesn't modify the string itself, it returns a new string. — Felix Kling
– Felix Kling, Commented Oct 12, 2013 at 5:34

thefourtheye · Accepted Answer · 2013-10-12 05:42:00Z

1

In javascript String is not mutable. So, when you do this.toUpperCase() it does not change the current string. Instead, it creates a new string with the uppercased letters in it.

If you want your example to work, you can do (as suggested by elclanrs in the comments)

fruits = fruits.myUcase();

answered Oct 12, 2013 at 5:42

thefourtheye

241k53 gold badges466 silver badges505 bronze badges

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

2 Comments

Jitender Over a year ago

But with Array prototype it is returning value. w3schools.com/js/tryit.asp?filename=tryjs_prototype_array

thefourtheye Over a year ago

@amit Correct. That is because, javascript Arrays are basically objects and so they are mutable by default. this[i]=this[i].toUpperCase(); this particular line, modifies each and every element. That is why you are able to see the result.

Collectives™ on Stack Overflow

How to add prototype in string object using javascript

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related