全选，反选，全不选整理

　　　　<input type="checkbox" class="chk" name="" id="" value=""/>
        <input type="checkbox" class="chk" name="" id="" value=""/>
        <input type="checkbox" class="chk" name="" id="" value=""/>
        <input type="checkbox" class="chk" name="" id="" value=""/>
        <input type="checkbox" class="chk" name="" id="" value=""/>
        <input type="checkbox" class="chk" name="" id="" value=""/>
        <input type="checkbox" class="chk" name="" id="" value=""/>
        <button onclick="fanxuan()">反选</button>
        <button onclick="quanxuan()">全选</button>
        <button onclick="quanbuxuan()">全不选</button>

    function fanxuan(){
        var chk = document.getElementsByClassName("chk");
        for (var i=0;i<chk.length;i++ ) {
            if(chk[i].checked){
                chk[i].checked = false;
            }else{
                chk[i].checked = true;
            }
        }
    }
        function quanxuan() {
        var aa = document.getElementsByClassName(‘chk‘);
        for(var i=0; i<aa.length; i++){
        if(aa[i].name==name){
            aa[i].checked = true;
        }
    }
}
        function quanbuxuan() {
        var bb = document.getElementsByClassName(‘chk‘);
        for(var i=0; i<bb.length; i++){
        if(bb[i].name==name){
        bb[i].checked = false;
        }
    }
}