OpenLayers

Class: Collection

ol/Collection~Collection 


import Collection from 'ol/Collection';

An expanded version of standard JS Array, adding convenience methods for manipulation. Add and remove changes to the Collection trigger a Collection event. Note that this does not cover changes to the objects within the Collection; they trigger events on the appropriate object, not on the Collection as a whole.

new Collection(opt_array, opt_options)

Collection.js, line 62
Name Type Description
array Array.<T>

Array.
options

Collection options.

Name Type Default Description
unique boolean false

Disallow the same item from being added to the collection twice.

Methods

clear()

Collection.js, line 100

Remove all elements from the collection.

extend(arr){module:ol/Collection~Collection.<T>}

Collection.js, line 113

Add elements to the collection. This pushes each item in the provided array to the end of the collection.

Name Type Description
arr Array.<T>

Array.
Returns:
This collection.

forEach(f)

Collection.js, line 127

Iterate over each element, calling the provided callback.

Name Type Description
f function

The function to call for every element. This function takes 3 arguments (the element, the index and the array). The return value is ignored.

getArray(){Array.<T>}

Collection.js, line 142

Get a reference to the underlying Array object. Warning: if the array is mutated, no events will be dispatched by the collection, and the collection's "length" property won't be in sync with the actual length of the array.

Returns:
Array.

getLength(){number}

Collection.js, line 162

Get the length of this collection.

Returns:
The length of the array.

insertAt(index, elem)

Collection.js, line 172

Insert an element at the provided index.

Name Type Description
index number

Index.
elem T

Element.

item(index){T}

Collection.js, line 152

Get the element at the provided index.

Name Type Description
index number

Index.
Returns:
Element.

pop(){T|undefined}

Collection.js, line 188

Remove the last element of the collection and return it. Return undefined if the collection is empty.

Returns:
Element.

push(elem){number}

Collection.js, line 198

Insert the provided element at the end of the collection.

Name Type Description
elem T

Element.
Returns:
New length of the collection.

remove(elem){T|undefined}

Collection.js, line 213

Remove the first occurrence of an element from the collection.

Name Type Description
elem T

Element.
Returns:
The removed element or undefined if none found.

removeAt(index){T|undefined}

Collection.js, line 230

Remove the element at the provided index and return it. Return undefined if the collection does not contain this index.

Name Type Description
index number

Index.
Returns:
Value.

setAt(index, elem)

Collection.js, line 244

Set the element at the provided index.

Name Type Description
index number

Index.
elem T

Element.