Remove special symbols and extra spaces and replace with underscore using the replace method

Your regular expression [^a-zA-Z0-9]\s/g says match any character that is not a number or letter followed by a space.

Remove the \s and you should get what you are after if you want a _ for every special character.

var newString = str.replace(/[^A-Z0-9]/ig, "_");

That will result in hello_world___hello_universe

If you want it to be single underscores use a + to match multiple

var newString = str.replace(/[^A-Z0-9]+/ig, "_");

That will result in hello_world_hello_universe

It was not asked precisely to remove accent (only special characters), but I needed to.

The solutions givens here works but they don’t remove accent: é, è, etc.

So, before doing epascarello’s solution, you can also do:

var newString = "développeur & intégrateur";

newString = replaceAccents(newString);
newString = newString.replace(/[^A-Z0-9]+/ig, "_");
alert(newString);

/**
 * Replaces all accented chars with regular ones
 */
function replaceAccents(str) {
  // Verifies if the String has accents and replace them
  if (str.search(/[\xC0-\xFF]/g) > -1) {
    str = str
      .replace(/[\xC0-\xC5]/g, "A")
      .replace(/[\xC6]/g, "AE")
      .replace(/[\xC7]/g, "C")
      .replace(/[\xC8-\xCB]/g, "E")
      .replace(/[\xCC-\xCF]/g, "I")
      .replace(/[\xD0]/g, "D")
      .replace(/[\xD1]/g, "N")
      .replace(/[\xD2-\xD6\xD8]/g, "O")
      .replace(/[\xD9-\xDC]/g, "U")
      .replace(/[\xDD]/g, "Y")
      .replace(/[\xDE]/g, "P")
      .replace(/[\xE0-\xE5]/g, "a")
      .replace(/[\xE6]/g, "ae")
      .replace(/[\xE7]/g, "c")
      .replace(/[\xE8-\xEB]/g, "e")
      .replace(/[\xEC-\xEF]/g, "i")
      .replace(/[\xF1]/g, "n")
      .replace(/[\xF2-\xF6\xF8]/g, "o")
      .replace(/[\xF9-\xFC]/g, "u")
      .replace(/[\xFE]/g, "p")
      .replace(/[\xFD\xFF]/g, "y");
  }

  return str;
}

Source: https://gist.github.com/jonlabelle/5375315

Remove the \s from your new regex and it should work - whitespace is already included in "anything but alphanumerics".

Note that you may want to add a + after the ] so you don't get sequences of more than one underscore. You can also chain onto .replace(/^_+|_+$/g,'') to trim off underscores at the start or end of the string.

If you have a text as

var sampleText ="ä_öü_ßÄ_ TESTED Ö_Ü!@#$%^&())(&&++===.XYZ"

To replace all special character (!@#$%^&())(&&++= ==.) without replacing the characters(including umlaut)

Use below regex

sampleText = sampleText.replace(/[`~!@#$%^&*()|+-=?;:'",.<>{}[]\/\s]/gi,'');

OUTPUT : sampleText = "ä_öü_ßÄ____TESTED_Ö_Ü_____________________XYZ"

This would replace all with an underscore which is provided as second argument to the replace function.You can add whatever you want as per your requirement