How do Javascript getters work?

Question

i'v been using javascript getters for a long time in my applications, and always thought

that they work like this:

myobject.prototype.__defineGetter__('something', function () {
   return DoSomeHeavyComputation() // this will be executed only once and will be saved
})

new myobject()
myobject.something // the computation will be done here
myobject.something // no computation will be done here.

i just found out the computation is done each time...

is there a resource or something that shows how do they actually work ?

It's just a function, lifer any other. You could cache the value, for example by executing a function that returns a function. — Dave Newton
– Dave Newton, Commented May 16, 2012 at 0:13

Amjad Masad · Accepted Answer · 2012-05-15 23:58:11Z

1

If you define a getter on a property of an object it will be called each time you try to access that property.

obj.prop;

If you want to cache the result you should do it manually.

Similary if you define a setter on a property of an object it will be called each time you set the property.

obj.prop = 1;

answered May 15, 2012 at 23:58

Amjad Masad

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brandwaffle · Accepted Answer · 2012-05-15 23:48:39Z

0

This article is awesome and gets really into the nitty-gritty of prototyping and object instantiation: http://dmitrysoshnikov.com/ecmascript/chapter-7-2-oop-ecmascript-implementation/

answered May 15, 2012 at 23:48

brandwaffle

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timrwood · Accepted Answer · 2012-05-16 23:37:48Z

0

I think you are looking for something like memoization.

http://documentcloud.github.com/underscore/#memoize

answered May 16, 2012 at 23:37

timrwood

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