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

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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(",");