[Js] getClass, display:none, block

function showLayer( obj, area ) {

var mapDataList = document.getElementsByClassName("mapDataList");

document.getElementById("city1").innerHTML = obj;

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

mapDataList[i].style.display = "none";

}

document.getElementById(area).style.display = "block";

}