how to allow space?

the below javascript code prevent user to put all special character including "space".

1. through same function, I need to allow "space"..how to do this..please help

2. however user is unable to type any special character, but user can copy/paste special character. Is there any way to prevent this also...one way disable right click on page..any other way..please suggest!

   function isValidSearchText(evt) {
       var charCode = (evt.which) ? evt.wh开发者_JS百科ich : event.keyCode;
       if ((charCode < 48 || charCode > 57) && (charCode < 97 || charCode > 122) && (charCode < 65 || charCode > 90))
           return false;
       return true;
   }
   

Change the if-statement from this

if ((charCode < 48 || charCode > 57) && ....

To this:

if (charCode != 32 && (charCode < 48 || charCode > 57) && ...