[javascript] how to check 01 02 number

Question

 var val= $('#num').val(); // 01
     if(isNaN(val) || val > 59 || val== ''){
   alert("error");
 }

In this case, has not alert error

       var val= $('#num').val(); // 01
       val = parseInt(val);

Answer 1

Well you code has no val in it, guessing it is a typo.

isNaN(val) <-- checking to see if a string is a number?

val > 59 <-- comparing string vs a number. NOT a number vs Number

val== '' <-- seeing if a string is matching nothing

You want to use parseInt() for the second check. Read the linked page.

Answer 2

You need to:

• Define a variable name: var yourVariable = "01";

• Then use typeof to find its type: typeof(yourVariable);

typeof will return "string", in my example. It can also return "number" or "undefined" - very useful.