[javascript] Regex for empty string or white space

I am trying to detect if a user enter whitespace in a textbox:

 var regex = "^\s+$" ; 
 if($("#siren").val().match(regex)) {
     echo($("#siren").val());
     error+=1;
    $("#siren").addClass("error");
    $(".div-error").append("- Champ Siren/Siret ne doit pas etre vide<br/>");
 }

if($("#siren").val().match(regex)) is supposed to match whitespace string, however, it doesn' t seems to work, what am I doing wrong ?

Thanks for your helps

If you are looking for empty string in addition to whitespace you meed to use * rather than +

var regex = /^\s*$/ ;
                ^

http://jsfiddle.net/DqGB8/1/

This is my solution

var error=0;
var test = [" ", "   "];
 if(test[0].match(/^\s*$/g)) {
     $("#output").html("MATCH!");
     error+=1;
 } else {
     $("#output").html("no_match");
 }

If you're using jQuery, you have .trim().

if ($("#siren").val().trim() == "") {
  // it's empty
}

If one only cares about whitespace at the beginning and end of the string (but not in the middle), then another option is to use String.trim():

"    your string contents  ".trim();

// => "your string contents"

Had similar problem, was looking for white spaces in a string, solution:

• To search for 1 space:

  var regex = /^.+\s.+$/ ;
  

  example: "user last_name"

• To search for multiple spaces:

  var regex = /^.+\s.+$/g ;
  

  example: "user last name"