CODEWITHSUNDEEP
javascriptasp.netdom-events
Janet
Janet

Reputation: 1411

User should not be allowed to type zero as the first digit using JavaScript

I need to validate a number entered by a user in a textbox using JavaScript. The user should not be able to enter 0 as the first digit like 09, 08 etc, wherein he should be allowed to enter 90 , 9.07 etc..

Please help me.. I tried to use the below function but it disallows zero completely:

   function AllowNonZeroIntegers(val)
   {
   if ((val > 48 && val < 58) || ((val > 96 && val < 106)) || val == 46 || val == 8 || val == 127 || val == 189 || val == 109 || val == 45 || val == 9)
           return true;
       return false;
   }

on

 Texbox1.Attributes.Add("onkeypress", "return AllowNonZeroIntegers(event.keyCode)");   
 Texbox1.Attributes.Add("onkeydown", "return AllowNonZeroIntegers(event.keyCode)");

Upvotes: 1

Views: 2458

Answers (2)

Mrchief
Mrchief

Reputation: 76218

Ty this:

Texbox1.Attributes.Add("onkeydown", "return AllowNonZeroIntegers(event)");

function AllowNonZeroIntegers(e) {
    var val = e.keyCode;
    var target = event.target ? event.target : event.srcElement;
    if(target.value.length == 0 && val == 48) {
        return false;
    }
    else if ((val >= 48 && val < 58) || ((val > 96 && val < 106)) || val == 46 || val == 8 || val == 127 || val == 189 || val == 109 || val == 45 || val == 9) {
        return true;
    }
    else {
        return false;
    }
}

Demo

Upvotes: 0

Robert
Robert

Reputation: 8767

Use charAt() to control the placement of X at Y:

function checkFirst(str){
   if(str.charAt(0) == "0"){
       alert("Please enter a valid number other than '0'");
   }
}

Upvotes: 3

Related Questions