Collection in Salesforce Lightning.

TOPICS TO COVERED:

1)Array
2)List
3)Map
4)Set

Let's discuss in detail,

1)Array

To define the attribute for storing array values we can write:

<aura:attribute type="String[]" name="arrayattribute" default="['Apple','Orange','Mango']" />

• Here we are storing some default values in "arrayattribute".
• An array is a collection of the defined data types.
• Setting a default value without square brackets is deprecated and can lead to unexpected behavior.

2)List


To define the attribute for storing values in order we can write:

<aura:attribute type="List" name="Listattribute" default="['Apple','Orange','Mango']" />

• Here we are storing some default values in "Listattribute".
• The list can have duplicates as well.
• Setting a default value without square brackets is deprecated and can lead to unexpected behavior.

3)Map


To define the attribute for mapping keys to values.

<aura:attribute type="Map" name="Mapattribute" default="{1:'value1',2:'value2'}" />

• Here we are storing some default values in "Mapattribute".
• A map cannot have duplicate keys.
• A collection maps keys to values.  Each key can map to at most one value. Defaults to an empty object, {}. 
• Retrieve values by using cmp.get("v.Mapattribute")['1'].

4)Set


To define the attribute for Values which are unique.

<aura:attribute type="Set" name="Setattribute" default="['Apple','Orange','Mango']" />

• Here we are storing some default values in "Setattribute".
• The set cannot have duplicate values.
• Order for the set item is not as it is when values are returned, It may be in the same order or may change.
• Setting a default value without square brackets is deprecated and can lead to unexpected behavior.