js实现CkeckBox全选与反选

function SelectAll(){
        var check = document.getElementsByTagName("input"); // 获取所有input标签
        var all   = document.getElementById(‘all‘); // 获取全选按钮
        if(all.checked){
            for(var i=0;i<check.length;i++){
                if(check[i].getAttribute("type")=="checkbox"){
                    check[i].checked = true;
                }
            }
        }else{
            for(var i=0;i<check.length;i++){
                if(check[i].getAttribute("type")=="checkbox"){
                    check[i].checked = false;
                }
            }

}
    }