Using JavaScript namespacing

Question

I am trying to convert this code to a namespace to make it cleaner and to avoid polluting the global namespace. I'm fairly new to this, and could use a little guidance or examples how I would convert the following code into a javascript namespace.

function Validator(fields) {
     this.fields = fields;
}

Validator.prototype.validate = function(form) {
  for(var i = 0, l=this.fields.length; i < l; i++) {
    alert(this.fields[i].value);
        if (this.fields[i].value == 0) {
            alert("The field  is empty");
            return false;
        }
    }
}

var validator = new Validator([ "username", "password"]);

function runValidate(form) {
validator.validate(form);
    }

(I know this OO approach to validation is excessive!) I call this runValidate from a button in a form like this "runValidate(this.form)".

Is that runValidate function really necessary? It saves you only 7 chars. — Bergi
– Bergi, Commented Feb 27, 2013 at 10:14
Just directly call validator.validate(this.form) from the button — Bergi
– Bergi, Commented Feb 27, 2013 at 13:43

Rafał Rutkowski · Accepted Answer · 2013-02-27 10:35:08Z

2

Namespaces are just javascript objects, for example

var myNamespace = {};
myNamespace.Validator = function(fields) {
   ...
}
myNamespace.Validator.prototype.validate = function(form) {
   ...
}

answered Feb 27, 2013 at 10:35

Rafał Rutkowski

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3 Comments

Jose the hose Over a year ago

Thanks for your answer. Should I do the same with my runValidate function? how would I set var validator?

Jose the hose Over a year ago

would var validator = new Validator([ "username", "password"]); become var validator = new myNamespace.Validator([ "username", "password"]); ?

Rafał Rutkowski Over a year ago

Correct, you now call new myNamespace.Validator instead of new Validator. And then use validator.validate, as @Bergi suggested, I see no point in having runValidate function.

cezar · Accepted Answer · 2013-02-27 10:50:02Z

1

Javascript doesn't have native namespaces but you could use plain and simple objects to simulate that. Here's a simple implementation of a namespace utility function:

function namespace(namespaceString) {
  var nodes = namespaceString.split('.'),
      parent = window,
      currentNode;    

  for(var i = 0, length = nodes.length; i < length; i++) {
    currentNode = nodes[i];
    parent[currentNode] = parent[currentNode] || {};
    parent = parent[currentNode];
  }

  return parent;
}

You can use like this:

var MyApp = namespace("MyApp");
MyApp.Validator = function(fields) {
  this.fields = fields;
}

var validator = new MyApp.Validator(["username", "password"]);
// this also works:
var validator = new namespace("MyApp.Validator")(["username", "password"]);

This will keep you from poluting your global namespace but you will still have some global variables: MyApp in this case and any other root node in your namespaces.

answered Feb 27, 2013 at 10:50

cezar

563 bronze badges

2 Comments

Jose the hose Over a year ago

Many thanks. Would the function call from the button in the form remain the same?

cezar Over a year ago

Yes. Even if it's not the best way to go, it should work just fine.

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