Difference between conventions

Question

Just wanted to know if anyone could explain the difference between these two conventions:

if ( !object ) 

if ( object == null )

where object is an instance of a user-defined class.

I'm sure these two cannot be used interchangeably, or are they?

Thank.

Answer 1

The effect is the same in practice, so I think you could say that they are interchangeable.

In a boolean context (for example, conditional), the expression evaluates to both true and false.

In ActionScript 3.0, the following values ​​are evaluated as false:

• Lying
• Null
• 0
• NaN
• "" (empty line)
• undefined
• invalid

Everything else evaluates to true.

A reference to a custom instance of a class can be either null or not null.

So in this case:

if ( object == null )

, , null.

:

if ( !object )

object false, object - null. null, . , , . , , object null, . , , object null, .

, ; ; , false , null; , , null, null. .

Answer 2

- . , not (!) true, , false, .

, null .

, , , 0, false, null ( "\ 0" ) .

ActionScript, false, null, 0 .. .

Answer 3

, :) , , ; - true, .

"!" " " "==" , ,