How to know if a variable is defined in Javascript? Which function I can use?

Thanks in advance.

Alert it by name?

<script language ="javascript">
var 1 = ("1")

alert(1)
</script>

The alert should return 1.

HTH
interrupt

You can use typeof...
However typeof will return "undefined" if a variable has not been set to any value / object / etc., so var myVar; would return "undefined" and var myVar = null; would not.

HTH,

Chris

Also, 1 is not a valid variable name; it's a value.

var a1 = ("1")

alert(a1)

would work.....

Imar