window.onload = function(){inputDir();}

 function inputDir()
 {
     numOfForms = document.forms.length;
     for(x=0;x<numOfForms;x++)
     {
         currentForm = document.forms[x];
         numOfElements = currentForm.length;
         for(z=0;z<numOfElements;z++)
         {
             if(currentForm[z].type == "text" || currentForm[z].type == "textarea")
             {
                element = currentForm[z];

                

            (function(element) { 
                 if(element.addEventListener)
                 {
                    element.addEventListener('keyup', function() {
                     chooseDir(element);
                     }, false);
                 }
                 else
                 {
                    element.attachEvent('onkeyup', function() {
                    chooseDir(element);
                    }, false);

                 }
             })(element);

             }
         }
     }
 }
 function chooseDir(input)
 {

     rtlChars= '\u0600-\u06FF';
     rtlChars+= '\u0750-\u077F';
     rtlChars+= '\uFB50-\uFDFF';
     rtlChars+= '\uFE70-\uFEFF';
     
     controlChars= '\u0000-\u0020';
        controlChars+= '\u2000-\u200D';

     value = input.value;

     var reRTL     = new RegExp('^[' + controlChars + ']*[' + rtlChars + ']');
     var reControl = new RegExp('^[' + controlChars + ']*$');

     if(value.match(reRTL))
     {
            input.dir = 'rtl';
     }
     else if(value.match(reControl))
     {
         return false;
     }
     else
     {
         input.dir = "ltr";
     }

 }