CODEWITHSUNDEEP
arraysactionscript-3
coner
coner

Reputation: 270

Assign a value at index out of bound

I have an array and I first check if the array has the index of given number. I like to assign a value at that index if the array has not got any.

var newArray:Array = [0,1,2,3];//length is 4
if(newArray[5] == "")//true
{
    newArray[5] = 5;
}

Adobe Help page says;

Inserting array elements

...

If the Array or Vector doesn’t already have an element at that index, the index is created and the value is stored there. If a value exists at that index, the new value replaces the existing one.

But I am not sure it is about null elements or undefined.

How can I assign a value to index that doesn't exist?

I can push till the given index but wondering is anything else possible.

Upvotes: 0

Views: 638

Answers (1)

BotMaster
BotMaster

Reputation: 2223

array reference its elements as not typed so if an element does not exist it can be only undefined (default value for untyped) so in your case no need to check for null or "", you only need to check for undefined.

if(newArray[5] == undefined)
{
    newArray[5] = 5;
}

EDIT:

undefined is a keyword in as3 that defines a default value for untyped objects. It is the value you use to check if an untyped object has no current value. (As opposed to a typed object that has null as default value with the exception of numbers). Using "" as you suggest doesn't work since it is a valid String value and would only work to check if a String object is not null and has a length of 0. Equivalent of String.length == 0.

The assignment is correct, even though the index 4 does not exist at this point the Array Object does not complain and assign the value to index 5.

Upvotes: 3

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