Simple validation javascript function

Question

I have this javascript function:

if (myform.telephone.value.length < 10){
jAlert ('Please enter at least 10 characters!',function(){$(myform.telephone).focus();});
return false;

If the user enters less than 10 characters, an alert is triggered. I need to modify the script so that the alert pops if the user enters less than 10 DIGITS (0,1,2,etc)..

How can i do this ?

thomaux · Accepted Answer · 2014-04-07 15:41:00Z

2

Update: As the OP correctly pointed out, there was a bug in the previous method. I advise not to use isNan as it is broken. I've updated the answer, code below.

This can be easily done by mathcing the input against a regular expression and then checking if the resulting number has 10 or more digits. Like:

var validate = function(){
    var number = tryParseNumber(input.value);
    if(number.toString().length < 10){
        alert("Invalid input");
    } else {
        alert("Valid output: " + number);
    }
};

var tryParseNumber = function (value) {
  if(/^(\-|\+)?([0-9]+|Infinity)$/.test(value))
    return Number(value);
  return false;
}

See this Fiddle for a working example.

edited Apr 7, 2014 at 15:41

answered Apr 7, 2014 at 11:43

thomaux

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Comments

Ashish Ratan · Accepted Answer · 2014-04-07 11:39:36Z

Try :

function phonenumber(inputtxt)  
{  
  var phoneno = /^\d{10}$/;  
  if((inputtxt.value.match(phoneno))  
        {  
      return true;  
        }  
      else  
        {  
        alert("message");  
        return false;  
        }  
}

To valid a phone number like XXX-XXX-XXXX XXX.XXX.XXXX XXX XXX XXXX

function phonenumber(inputtxt)  
{  
  var phoneno = /^\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/;  
  if((inputtxt.value.match(phoneno))  
        {  
      return true;  
        }  
      else  
        {  
        alert("message");  
        return false;  
        }  
}

If you want to use a + sign before the number in the following way +XX-XXXX-XXXX +XX.XXXX.XXXX +XX XXXX XXXX use the following cod

function phonenumber(inputtxt)
{
  var phoneno = /^\+?([0-9]{2})\)?[-. ]?([0-9]{4})[-. ]?([0-9]{4})$/;
  if((inputtxt.value.match(phoneno))
        {
      return true;
        }
      else
        {
        alert("message");
        return false;
        }
}

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