How to create comma seperated value in javascript on selection of values from multiple selection select box?

I need the values selected from multipleselect select box as commaseperated values so that I can use these values in AJAX call to fetch the data fro开发者_StackOverflow中文版m db table using these values.

Please help to me..

Thanks

Assuming multiSelect is the select DOM object (obtained by document.getElementById for instance), then resultString will be the string you are looking for.

 var resultArray = [];
 for(var i=0; i < multiSelect.options.length; i++) {
     if (multiSelect.options[i].selected) {
         resultArray.push(multiSelect.options[i].value);
     }
  }
  var resultString = resultArray.join(",");