(IE9 ) document.getElementsByClassName ( , , querySelectorAll, ...), , , t . - , .
var nodes = document.getElementsByTagName('*'),
targetClass = 'myclass',
result = [];
for(var i = 0, l = nodes.length; i < l; i++){
if((nodes[i].className + ' ').indexOf(targetClass + ' ') !== -1){
result.push(nodes[i]);
}
}
getElementsByClassName, NodeList, .