I want to check that if my username contains space so then it alert so i do this it work but one problem i am facing is that if i give space in start then it does not alert.I search it but can't find solution, my code is this

var username    =   $.trim($('#r_uname').val());
var space = " ";
  var check = function(string){
   for(i = 0; i < space.length;i++){
     if(string.indexOf(space[i]) > -1){
         return true
      }
   }
   return false;
  }

  if(check(username) == true)
  {
     alert('Username contains illegal characters or Space!');
     return false;
  }

I want to check that if my username contains space so then it alert so i do this it work but one problem i am facing is that if i give space in start then it does not alert.I search it but can't find solution, my code is this

var username    =   $.trim($('#r_uname').val());
var space = " ";
  var check = function(string){
   for(i = 0; i < space.length;i++){
     if(string.indexOf(space[i]) > -1){
         return true
      }
   }
   return false;
  }

  if(check(username) == true)
  {
     alert('Username contains illegal characters or Space!');
     return false;
  }

• javascript
• jquery

• 1 Regular Expressions. Also, you're trimming the string, so how could there be a space at the beginning of it? – user788472 Commented Apr 7, 2013 at 4:22
• I use trim bt in db it dont remove space – Azam Alvi Commented Apr 7, 2013 at 4:35
• 1 It sounds like you're saying that you want to find out if a string has a space at the beginning of it, but you're trimming that space off before you check. So the solution would be to not trim the string... – user788472 Commented Apr 7, 2013 at 4:55
• @Nathan Bouscal you was right.thanks – Azam Alvi Commented Apr 7, 2013 at 5:16

3 Answers 3

Just use .indexOf():

var check = function(string) {
    return string.indexOf(' ') === -1;
};

You could also use regex to restrict the username to a particular format:

var check = function(string) {
    return /^[a-z0-9_]+$/i.test(string)
};

You should use a regular expression to check for a whitespace character with \s:

if (username.match(/\s/g)){
    alert('There is a space!');
}

See the code in action in this jsFiddle.

why you don't use something like this?

if(string.indexOf(space) > -1){
     return true
  }