prototype

Summary

Returns a reference to the prototype for a class of number.

Syntax

number.prototype

Examples

The number argument is the name of a number. Use the prototype property to provide a base set of functionality to a class of objects. New instances of an object “inherit” the behavior of the prototype assigned to that object.

For example, to add a method to the Number object that returns the number of (integer) digits, declare the function, add it to Number.prototype , and then use it.

function number_digits() {
     var digits = 0;
     var num = this;
     while (num) >= 1) {
         digits++;
         num /= 10;
     }
     return digits;
 }

 Number.prototype.digits = number_digits;
 var myNumber = new Number(3456.789);
 document.write(myNumber.digits());
 // Output:
 // 4

Remarks

All intrinsic JavaScript objects have a prototype property that is read-only. Properties and methods may be added to the prototype, but the object may not be assigned a different prototype. However, user-defined objects may be assigned a new prototype.

The method and property lists for each intrinsic object in this language reference indicate which ones are part of the object’s prototype, and which are not.

Attributions

• Microsoft Developer Network: Article