DP_ObCollection

A DP_ObCollection is used to manage multiple instances of a JavaScript object as a single logical unit. Object instances stored in the collection are called “Members” of the collection. The DP_ObCollection assumes the following:

• The DP_ObCollection does not maintain any specific order of it members.
• Optionally all members of an DP_ObCollectionOrdered can be validated for type.
• A property of the specified Member object must contain a unique Key to be used as the member identifier.

Use the more advanced DP_ObCollectionOrdered if your application requires members to be maintained in order.

This component requires a JavaScript (ECMAScript) 1.3 (or better) environment and has been tested successfully on Internet Explorer 6+, Firefox 1+ and Opera 9+.

The component is available from GitHub:

• Direct Download (Master Branch, Zip format)
• GitHub Repository Home

All downloads and code are covered by our Source Code Policy.

The library consists of a single JavaScript file with a .JS extension.

Importing the Library

The library must be imported before it is used. To import the library use the <script> tag. For example:

<script type="text/javascript" src="DP_ObCollection.js"></script>

Your path may vary depending on the location of the script on your server.

Creating and Accessing the Object

Once the library has been imported you may create DP_ObCollection objects as you would any other JavaScript object. For example:

var MyCollection = new DP_ObCollection(...);

See the Constructor section for more information.

Once you have created an instance of the object you can use the methods and properties provided to add, manipulate, delete and access members and information about them. See the Examples section for some sample code.

DP_ObCollection()

There are several properties available in an ObOrderedCollection. However it is recommended that all access to these properties occur via their related method calls.

DP_ObCollection properties available:

• Members: A JavaScript array which contains references to all members of the collection. Access to this property is exposed via the getAll() method.
• MemberType: A reference to the Member constructor used to validate member type. Access to this property is exposed via the getMemberType() method.
• MemberKeyName: The name of the Member property to use as the unique member key. Access to this property is exposed via the getMemberKeyName() method.
• CreationDate: A date/time reference referering to the instantiation time of the collection. Access to this property is exposed via the CreationDate() method.

DP_ObCollection methods available:

• add()
• clear()
• drop()
• dropAll()
• get()
• getAll()
• getCount()
• getCreationDate()
• getKeys()
• getMemberKeyName()
• getMemberType()
• isEmpty()
• isMember()
• isValidType()

Note that in method/function signatures a pipe (“|”) indicates “OR” while arguments in square brackets are optional.

add()

drop()

dropAll() or clear()

get()

getAll()

getCount()

getCreationDate()

getKeys()

getMemberKeyName()

getMemberType()

isEmpty()

isMember()

isValidType()

Creating and Using a Collection

Let’s first create an instance of DP_ObCollection called “MyOptions”. Since we’re creating a collection of options we pass in the constructor for the Option class. We’ll use the “text” property of the Option class as our unique key.

	MyOptions = new DP_ObCollection("text", new Option().constructor);
	

Now we’ll create a few options and simultaneously add them to the collection using the add() method:

	MyOptions.add( new Option("Jim") );
	MyOptions.add( new Option("Carol") );
	MyOptions.add( new Option("Paxton") );
	MyOptions.add( new Option("Matilda") );
	MyOptions.add( new Option("Sandy") );
	MyOptions.add( new Option("Louise") );
	

Loop over the Collection and display the contents:

	for(var Cur in MyOptions.Members) {
		document.write("Current Option Text: " + Cur + "<br>");
	

June 8, 2013

• Initial GITHUB release.

August 22, 2005

• Changed the name of the component to “DP_ObCollection”.
• Cleaned up the method declaration procedure used in the object.

August 27, 2004

• Fixed several bugs with typeless collections.
• Reversed position of the contructor arguments to allow the “type” argument to be optional.

August 18, 2004

• Added ability to have typeless collections.

July 26, 2004

• Initial Release