Issue in Adding property to string object

Question

var s = "Hi";

Date.now = function (){
    return new Date();
}

s.createdOn = function (){
    return new Date();
}

alert(s.createdOn()); // This is not working
alert(Date.now()); // This works fine

Am i violating any rule. Because i can add new property to Date class but not to string class. why?

Is there any specific reason why you would want to extend specifically string in this way? A custom object might be a better fit and more logical. — KillerX
– KillerX, Commented Apr 14, 2012 at 7:24
I am just curious to know why it s not working. No any specific reason — deen
– deen, Commented Apr 14, 2012 at 7:34

Joseph · Accepted Answer · 2012-04-14 07:44:56Z

4

The reason you can't add properties or methods to a string literal is that when you try to access a literal's property or method, the Javascript interpreter temporarily copies the value of the string into a new object and then use that object's properties or methods. This means a String literal can only access a string's default properties or methods and those that have been added as prototypes.

More info can be obtained from this link:

http://www.hunlock.com/blogs/The_Complete_Javascript_Strings_Reference

Hope this will help you

edited Apr 14, 2012 at 7:44

Joseph

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answered Apr 14, 2012 at 7:34

UVM

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Comments

Joseph · Accepted Answer · 2012-04-14 07:35:08Z

1

replace:

var s = "Hi";

with

var s = {};

answered Apr 14, 2012 at 7:35

Joseph

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3 Comments

deen Over a year ago

May i know how t make diffence?

Joseph Over a year ago

it's explained with @UNNI's answer. and why are you appending methods to a string anyway?

deen Over a year ago

am just curious to know why it s not working. No any specific reason

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