cssスタイルに基づいて全選択を実現

function getByClass(cla, obj){
		var obj = obj || document, arr = [];
	 
		if(document.getElementsByClassName){
						return document.getElementsByClassName(cla);
		} else {
			var all = obj.getElementsByTagName('*');
					
			for(var i = 0, len = all.length; i < len; i++){
							if(all[i].className.match(cla) != null) arr.push(all[i]);
			}
					
			return arr;
		}
}
function checkAll(cla,obj){
	var checkboxs = getByClass(cla);
	var len = checkboxs.length;
	for(i=0;i<len;i++){
		checkboxs[i].checked = obj.checked;
	}
}		





      

   
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