Javascript : Array Length

length is a property of arrays in JavaScript that returns or sets the

number of elements in a given array.

Code:

var names= ["sagar","sangram","sachin"]

console.log(names.length)

/*we can set array length it will increase array by appending undefined

element at end*/

names.length =6;

console.log(names)

/*now array size got increased to 6 it added empty element to end to match

set size*/

console.log("Last:",names[5])

names[5] = "swapnil"

console.log("Last:",names[5])

console.log(names)

names.length =4;

console.log(names)

Output:

3

[ 'sagar', 'sangram', 'sachin', <3 empty items> ]

Last: undefined

Last: swapnil

[ 'sagar', 'sangram', 'sachin', <2 empty items>, 'swapnil' ]

[ 'sagar', 'sangram', 'sachin', <1 empty item> ]

Explanation:

when we can set array length it will increase array by appending undefined

element at end.When we set last element in increased array to string

"swapnil" by strar[5] = "swapnil" other element which got added due to

increase in length remain unchanged that is undefined or empty slot.When we

set array length to value less than its current array length array get

contracted in sence.When we set array length was 6 it become 6 element array

but when it is set to 4 ,5th & 6th element get removed.

Note:

names.length =-2; or names.length = 2.3 will give an error saying

'RangeError: Invalid array length'.