Implementing a builder using closures in JavaScript -

i implement builder using closures in javascript. feel can done, struggling put code.

i have feel there better solution leveraging partial application.

function builder() {     this.spec = {}; }  builder.prototype.withfoo = function(value) {     this.spec.foo = value;     return this; };  builder.prototype.withbar = function(value) {     this.spec.bar = value;     return this; };  builder.prototype.build = function() {     var result = {};     result.foo = this.spec.foo;     result.bar = this.spec.bar;     this.spec = {}; // avoid accidentally using same builder repeatedly.      return result; };  var builder = new builder(); builder.withfoo('foo value')        .withbar('foo value')        .build(); // { foo: 'foo value' , bar: 'bar value' } 

can me this?

edit: key thing here want object instantiated lazily.

here alternative approach:

function builder(obj){     return obj; } 

this called fowler , martin "identity builder" , quite common in enterprise architecture. has advantage of supporting arbitrarily nested hierarchies of objects , sub objects , generic.

var mybuildobject = builder({     spec: {          foo: foo,         bar: bar     } }); 

it more though, can specify arrays:

var mybuildobject = builder({     spec: [....] }); 

it can extended , subclassed more sophisticated builders can in turn return builder.call(this, obj) after decorating it.

it can specify getters/setters.