One other thing to keep in mind... when you define functions(methods) within your constructor function, every new object will have their own copy of that function definition. When the methods are defined on the prototype, that code is shared amongst all of the created objects.
_jason On Thu, Apr 14, 2011 at 12:00 AM, Max Vasiliev <[email protected]>wrote: > It's just another way to create object by some template (or prototype). > > Using "your" method: var o = Templater(); > Using prototype: var o = new Template(); // see the 'new' keyword > > Usage of created object is the same: o._supplant(...); > > But also there's few differences in creating derived objects. > > Using "your" method: > > function DerivedTemplater() { > var parent = Templater; > > parent.extraMethod = function() {}; > > return parent; > } > > Using prototype: > > function DerivedTemplater() { > } > > DerivedTemplater.prototype = new Templater(); > DerivedTemplater.prototype.constructor = DerivedTemplater; > > DerivedTemplater.prototype.extraMethod = function() {}; > > It's up to you which method to choose. > > Regards, > Max. > > > On Sat, Apr 9, 2011 at 9:46 AM, planon <[email protected]> wrote: > > I was reading Ben Cherry's blog post on Writing Testable Javascript > > and I came across this example: > > > > function Templater() { > > this._templates = {}; > > } > > > > Template.prototype = { > > _supplant: function(str, params) { > > for (var prop in params) { > > str.split("{" + prop +"}").join(params[prop]); > > } > > return str; > > }, > > render: function(name, params) { > > if (typeof this._templates[name] !== "string") { > > throw "Template " + name + " not found!"; > > } > > > > return this._supplant(this._templates[name], params); > > }, > > defineTemplate: function(name, template) { > > this._templates[name] = template; > > } > > }; > > > > > > > > http://www.adequatelygood.com/2010/7/Writing-Testable-JavaScript > > > > > > My question is why does he use prototype to extend this function > > rather than writing it as: > > > > function Templater(){ > > return { > > _supplant:function(){} > > > > etc... > > } > > } > > > > What is the use case for prototype-based extension? > > > > -- > > To view archived discussions from the original JSMentors Mailman list: > http://www.mail-archive.com/[email protected]/ > > > > To search via a non-Google archive, visit here: > http://www.mail-archive.com/[email protected]/ > > > > To unsubscribe from this group, send email to > > [email protected] > > > > -- > To view archived discussions from the original JSMentors Mailman list: > http://www.mail-archive.com/[email protected]/ > > To search via a non-Google archive, visit here: > http://www.mail-archive.com/[email protected]/ > > To unsubscribe from this group, send email to > [email protected] > -- To view archived discussions from the original JSMentors Mailman list: http://www.mail-archive.com/[email protected]/ To search via a non-Google archive, visit here: http://www.mail-archive.com/[email protected]/ To unsubscribe from this group, send email to [email protected]
