IsNull equivalent in ASP/jScript

hey folks

i usually code in VBscript and use IsNull - i understand the function does not exist in Jscript. what can be used instead?

(i am checking a database value - but its a general question too)

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Js has better aproach to Null management that VB in general lines... usually you cant evaluate a null value in VB, however, in Js a Null value can be evaluated to False without getting errors, this is because in Js all that is not True is always False, as Null can't be True it's automatically set to False when evaluated.

Also you can use a statement like (object == null) if you are not used to evaluate directly an object
kneidelsAuthor Commented:
wasnt sure exactly what you meant
i landed up using the length which seemed to help.

should that give the same indication?
Göran AnderssonCommented:
Checking the length would give you the same result for a null value and an empty string value, so that would only work for data types where only a null value is converted into an empty string and no other value. I.e. it would work for a numerical field, but not a text field.

You should be able to determine if a field contains null from it's status:

if (rs["field"].Status == adFieldIsNull) ...

If you don't have the ad constants defined, this one has the value three:

var adFieldIsNull = 3;


Checking a null value is different for a database result and null object refereces. A recordset doesn't use null references to represent null values from the database, instead a special Null object is used.

A null reference can easily be determined in JScript using the comparison (obj == null), which is equivalent to IsNothing(obj) in VBscript.

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kneidelsAuthor Commented:
great - thanks!
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