JavaScript Enumerator Object provides the functionality to wrap the collections such as Arrays or collection of items. JavaScript enumerator object enables you to read the items from the collection whose end point is not known. For example, if you have any array collection retrieved from any ActiveX object whose number of indexes is unpredictable then it can be passed to the Enumerator constructor to make it readable. JavaScript Enumerator does not support direct access to its collection item by passing the index of the item like in Arrays. You must use the JavaScript loop mechanism to read the items stored in the enumerator collection object. JavaScript for loop can be used to read the items of Enumerator collection object.
Syntax
var myEnum = new Enumerator( collection );
Parameters
collection: a collection type object.
myEnum: a variable name to which it assigns the created Enumerator object.
Above syntax of JavaScript Enumerator object shows that Enumerator class object constructor provides an overloaded constructor that accepts a parameter as collection type. You can pass the object of collection type such as Array to convert it into Enumerator. This will help you to read the items of collection one by one, but you cannot read the items easily by passing the index of the item. JavaScript Enumerator stores the items in a list and reads each item by moving its pointer from one item to another. Enumerator supports four methods that allow you to follow the mechanism of pointer movement to get the value of each item in the collection.
Methods
Following are the methods supported by the JavaScript Enumerator object that moves the pointer position to read the items:
- moveFirst(): it moves the pointer to the first item of Enumerator.
- atEnd(): returns Boolean value i.e. true/false according to the position of pointer. If pointer is at last item then it return true.
- item(): returns the value of item stored at the current pointer position.
- moveNext(): this method moves the pointer position towards the next item in the collection of Enumerator.
