Whether the JavaScript isNaN is a numeric function

The code is as follows	Copy Code
function CheckValue () { if (isNaN (Document.all.textbox.value)) { Alert ("Please use digital input!") "); return false; } }

Cases

Instance
In this case, we'll use Isfinite () to detect infinite numbers:

code is as follows

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<script Type= "Text/javascript" document.write (Isfinite (123))  //returns false document.write (1.23 )  //returns false document.write (Isfinite (5-2))  //returns false document.write (isfinite (0))   // return False document.write (Isfinite (0/0))  //return True document.write (isfinite ("Hello"))  //return True document.write (Isfinite ("2005/12/12"))  //return True document.write (Isfinite (True))  //return False document.write (isfinite (undefined))  //returns true </script>