JavaScript Date prototype
Example
Make a new date method that gives the date object a month-name property called myMonth:
Date.prototype.myMonth = function()
{
if (this.getMonth()==0) {return "January"};
if (this.getMonth()==1) {return "February"};
if (this.getMonth()==2) {return "March"};
if (this.getMonth()==3) {return "April"};
if (this.getMonth()==4) {return "May"};
if (this.getMonth()==5) {return "June"};
if (this.getMonth()==6) {return "July"};
if (this.getMonth()==7) {return "August"};
if (this.getMonth()==8) {return "September"};
if (this.getMonth()==9) {return "October"};
if (this.getMonth()==10) {return "November"};
if (this.getMonth()==11) {return "December"};
}
Make a Date object, then call the myMonth method:
const d = new Date();
let month = d.myMonth();
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Description
prototype allows you to add new properties and methods to dates.
prototype is a property available with all JavaScript objects.
Browser Support
prototype is an ECMAScript1 (JavaScript 1997) feature.
It is supported in all browsers:
| Chrome | Edge | Firefox | Safari | Opera | IE |
| Yes | Yes | Yes | Yes | Yes | Yes |
Syntax
Date.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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