Expand/Collapse extender using javascript

//Function to expand a particular section

function ExpandOnly(behId) {

    var listOfBehID =[];

    for (var i = 0; i < listOfBehID.length; i++) {

        var objCollapser = $find(listOfBehID[i]);

        if (behId.toLowerCase() == listOfBehID[i].toLowerCase()) {

            objCollapser._doOpen();//to expand

        }

        else {

            objCollapser._doClose();//to collapse

        }

    }

}