RegEx for Javascript to allow only alphanumeric

Question

I need to find a reg ex that only allows alphanumeric. So far, everyone I try only works if the string is alphanumeric, meaning contains both a letter and a number. I just w

Answer 1

Jquery to accept only NUMBERS, ALPHABETS and SPECIAL CHARECTERS

Enter Only Numbers: 




Enter Only Alphabets: 




Enter other than Alphabets and numbers like special characters: 

**JQUERY to accept only NUMBERS , ALPHABETS and SPECIAL CHARACTERS **



    $('#onlynumbers').keypress(function(e) {
      var letters=/^[0-9]/g; //g means global
      if(!(e.key).match(letters)) e.preventDefault();
    });

    $('#onlyalpha').keypress(function(e) {
      var letters=/^[a-z]/gi; //i means ignorecase
      if(!(e.key).match(letters)) e.preventDefault();
    });

    $('#speclchar').keypress(function(e) {
      var letters=/^[0-9a-z]/gi; 
      if((e.key).match(letters)) e.preventDefault();
    });