how to check that the first number is not 0 using javascript

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I want to validate a textbox such that no one can enter characters in textbox. for that my javascript code is :

C#

function isSpaceKey(evt) {
          //   debugger;
            var charCode = (evt.which) ? evt.which : event.keyCode

            if ((charCode < 47 || charCode > 57) &&  charCode != 8) {
                alert("Enter Numeral Values only!");
                return false;
            }


            return true;
        }

it is working fine but i want that the first number should not be 0. How can i do it? Thanks.

Posted 23-Jul-13 23:37pm

Rambo_Raja

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Dholakiya Ankit 24-Jul-13 5:58am

can u try evt.value.substring(0,1)!="0"

2 solutions

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Vindhyachal_Kumar · Answer 1 · 2013-07-24T00:02:00

Solution 1

Use this Code

C#

function vald1(objThis) {
            if (!(/^(?:[1-9]\d*|0)$/.test(objThis.value))) {
                alert("First number should not be '0'.");
                return false;
            }
            else
                return true;
        }

Posted 24-Jul-13 0:02am

Vindhyachal_Kumar

Ankur^\m/ · Answer 2 · 2013-07-24T00:06:00

There are many ways to do that.

Simplest in your case would be to check the length of the the text in the textbox. For length = 0 i.e first character, just don't allow 0 (key code 48) otherwise go with your normal validation. So change your code to:

JavaScript

function isSpaceKey(evt) {
    //   debugger;
    var charCode = (evt.which) ? evt.which : event.keyCode
    if (document.getElementById("TextBoxID").value.length == 0) { //for first character
        if (charCode == 48) {
            alert("Enter Numeral Values only!");
            return false;
        }
    }
    else {
        if ((charCode < 47 || charCode > 57) && charCode != 8) {
            alert("Enter Numeral Values only!");
            return false;
        }
    }

    return true;
}

Hope that helps!

Edit - I misread the question before. Updated the answer as per your requirement.