JavaScript如何判断节点是否存在(2)-木庄网络博客

放到代码里

<script type="text/javascript">
            var number = (1+Math.random()*(8-1)).toFixed(0);
            var oBox2=document.getElementsByTagName('div')[0];
            var oBox1=document.getElementById('box1');
            if(number<3){
                document.body.removeChild(oBox1);
            }
            if(document.getElementById('box1')){
                oBox2.className=oBox2.className+' box22';
                console.log(111);
            }
            else{
                oBox2.className='box2';
            }
        </script>

jquery方法

<script src="jquery-1.8.3.min.js"></script>
        <script type="text/javascript">
            var number = (1+Math.random()*(8-1)).toFixed(0);
            if(number>3){
            }
            else{
                $('#box1').remove();
            }
            if($('#box1').length>0){//判断
                $('.box2').addClass('box22');
            }
            else{
                $('.box2').removeClass('box22');
            }
        </script>

<script src="jquery-1.8.3.min.js"></script>
        <script type="text/javascript">
            var number = (1+Math.random()*(8-1)).toFixed(0);
            if(number>3){
            }
            else{
                $('#box1').remove();
            }
            if($('#box1')[0]){//判断
                $('.box2').addClass('box22');
            }
            else{
                $('.box2').removeClass('box22');
            }
        </script>