Method chaining in javascript

Question

This working code is using Sproutcore:

person = SC.Object.create({
    firstName: 'Foo',
    lastName: 'Bar',
    fullName: function() {
        return this.get('firstName') + " " + this.get('lastName');
    }.property()

});

console.log(person.get('fullName')); // "Foo Bar"

I wonder where property() is declared and how they have made this to work. When I try to reconstruct this without the SC class, it gives me:

TypeError: Object function () {
        return this.get('firstName') + " " + this.get('lastName');
    } has no method 'property'

How does the code looks like to make it work?

Jonathan Fingland · Accepted Answer · 2010-11-05 13:34:15Z

3

Sproutcore is extending the function prototype.

Function.prototype.property = function() { /* code here */ };

The specific code use by sproutcore is at https://github.com/sproutcore/sproutcore/blob/master/frameworks/runtime/core.js#L908

SC.mixin(Function.prototype, 
//...snip...

property: function() {
    this.dependentKeys = SC.$A(arguments) ;
    var guid = SC.guidFor(this) ;
    this.cacheKey = "__cache__" + guid ;
    this.lastSetValueKey = "__lastValue__" + guid ;
    this.isProperty = YES ;
    return this ;
  },
//snip
);

In their case, they are using their own mixin method, but the concept is the same: extending the prototype

edited Nov 5, 2010 at 13:34

answered Nov 5, 2010 at 13:15

Jonathan Fingland

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Comments

Matt Ball · Accepted Answer · 2010-11-05 13:16:11Z

1

Presumably, Sproutcode has modified Function.prototype to include a property function.

You could just look at the source code.

answered Nov 5, 2010 at 13:16

Matt Ball

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3 Comments

ajsie Over a year ago

Yeah im new to programming. How am I supposed to know where the code for this resides?

Matt Ball Over a year ago

@weng: google.com, or just look at the SproutCore web site (also found through Google) sproutcore.com/documentation

Matt Ball Over a year ago

@weng: oh! sorry. Well, that's what github search is for. Unfortunately, it seems to be down right now: github.com/…

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