How do you create a method for a custom object in JavaScript?

by

You can see from the answers that you have already that there is more than one way. 

#1
var o = new Object();
o.method = function(){}

#2
var o = new Object();
o.prototype.method = function(){}

#3
function myObject() {
    this.method = function(){}
}
var o = new myObject();

#4
function myObject() {}
myObject.prototype.method = function(){}
var o = new myObject();

#5
var o = {
    method: function(){}
}

#3 and #4 are using a constructor function. this means you can use them to create a number of objects of the same ‘class’ (classes don’t really exist in JavaScript)

#4 is different to #3 because all objects constructed with #4 will share an identical ‘method’ method because it is a property of their prototype. This saves memory (but only a very tiny amount) and if you change the method of the prototype, all #4 objects will immediately be updated – even if they’ve already been instantiated.

#1, #2 and #5 are all pretty much equivalent. This is because there will probably only ever be one of them at a time, so the fact that #2 has the method added to the prototype doesn’t really matter. (not taking cloning into account)

There are still more ways of adding methods to objects using factories with closure or adding ‘static’ properties/methods to functions or private nested functions… 🙂

More Related Contents:

  1. How to display all methods of an object?
  2. How to get all the values associated with an object in array?
  3. How to remove all duplicates from an array of objects?
  4. How to get a subset of a javascript object’s properties
  5. Creating object with dynamic keys [duplicate]
  6. How do I create a dynamic key to be added to a JavaScript object variable [duplicate]
  7. Sort array of objects by single key with date value
  8. Is it possible to get the non-enumerable inherited property names of an object?
  9. How do you check if a JavaScript Object is a DOM Object?
  10. How does the new operator work in JavaScript?
  11. How to add an object to an array
  12. Iterate through object properties
  13. Clone Object without reference javascript [duplicate]
  14. Why Array.indexOf doesn’t find identical looking objects
  15. How do I call a dynamically-named method in Javascript?
  16. Which way is best for creating an object in JavaScript? Is `var` necessary before an object property?
  17. Why in JavaScript both “Object instanceof Function” and “Function instanceof Object” return true?
  18. JSON.stringify function
  19. In javascript how can I dynamically get a nested property of an object
  20. Can a JavaScript object property refer to another property of the same object? [duplicate]
  21. JavaScript: Remove duplicates of objects sharing same property value
  22. How to create Javascript constants as properties of objects using const keyword?
  23. Multiple arguments vs. options object
  24. How do I count a JavaScript object’s attributes? [duplicate]
  25. Get the property of the difference between two objects in javascript
  26. Object referencing its own property on initialization [duplicate]
  27. Converting Array of Objects into Array of Arrays
  28. Using non-ASCII character as JavaScript object key [duplicate]
  29. Difference between ( for… in ) and ( for… of ) statements?
  30. Find object having maximum value for the `id` property in an array of objects

Leave a Comment