CODEWITHSUNDEEP
javascriptprototype-programming
user142019
user142019

Reputation:

If a prototype is changed, will this affect current instances?

Say I have this:

var _JS = function() {
  this.Constants = {
    True: 1,
    False: 0,
    Nil: null,
    Unknown: void(0),
  };
};

var JS = new _JS();

If I change it afterwards (add methods, using _JS.prototype.etc), can I call those methods on JS?

Upvotes: 2

Views: 886

Answers (4)

JAAulde
JAAulde

Reputation: 19560

Yes, a prototype change affects all instances of the item whose prototype you modified.

See example of a simple prototype modification: http://jsfiddle.net/JAAulde/56Wdw/1/

Upvotes: 5

Thaddee Tyl
Thaddee Tyl

Reputation: 1214

The following code would print something:

var ajs = new _JS();
_JS.prototype.do = function () {console.log('something');}
ajs.do();

Upvotes: 3

cwallenpoole
cwallenpoole

Reputation: 82028

Yes. Modifying a prototype modifies all instances.

A simple test:

var f = function(){}
var g = new f()
f.prototype.trace = function(){alert(1)}
g.trace(); // alerts 1

Upvotes: 5

Tomalak
Tomalak

Reputation: 338218

If a prototype is changed, will this affect current instances?

Yes. If you change the prototype that existing object instances share, it will change for all of them.

Upvotes: 3

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