JavaScript Number prototype
Example
Create a new number method that returns a number's half value:
Number.prototype.myMethod = function()
{
return this.valueOf() / 2;
};
Use the new method on a number:
let n = 55;
let x = n.myMethod();
Try it Yourself »
Definition and Usage
prototype allows you to add new properties and methods to numbers.
prototype is a property available with all JavaScript objects.
Syntax
Number.prototype.name = value
Warning
You are not advised to change the prototype of an object that you do not control.
You should not change the prototype of built in JavaScript datatypes like:
- Numbers
- Strings
- Arrays
- Dates
- Booleans
- Function
- Objects
Only change the prototype of your own objects.
The prototype Property
The JavaScript prototype property allows you to add new properties to objects:
Example
function Person(first, last, age, eyecolor) {
this.firstName = first;
this.lastName = last;
this.eyeColor = eyecolor;
}
Person.prototype.nationality = "English";
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Browser Support
Number.prototype is an ECMAScript1 (ES1) feature.
ES1 (JavaScript 1997) is fully supported in all browsers:
| Chrome | IE | Edge | Firefox | Safari | Opera |
| Yes | Yes | Yes | Yes | Yes | Yes |
