prototype Property (Date)


Returns a reference to the prototype for a date.


The date argument is the name of an object.

Use the prototype property to provide a base set of functionality to a Date. New instances of an object "inherit" the behavior of the prototype assigned to that object.

For example, to add a method to the Date object that returns the value of the largest element of the array, declare the function, add it to Date.prototype, and then use it.

function max( ){
    var max = new Date();
    max.setFullYear(2200, 01, 01);
    return max;
Date.prototype.maxDate = max;
var myDate = new Date();

if (myDate < myDate.maxDate())
    document.write("today isn't the max");
else if (myDate == myDate.maxDate())
    document.write("today is the max"); 

// Output:
// today isn't the max

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.


Supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards, Internet Explorer 8 standards, Internet Explorer 9 standards, Internet Explorer 10 standards, Internet Explorer 11 standards. Also supported Store apps (Windows 8 and Windows Phone 8.1). See Version Information.