点击切换代码记录

分别将切换按钮的css类定义为qiehuan；
显示部分css类定义为neirong；默认第一个按钮actived，内容第一个增加show；

.neirong {display:none;}
.show {display: block !important;}

.qiehuan .actived;
.neirong .show;

<script>
var aButton = document.getElementsByClassName("qiehuan");
var aContent = document.getElementsByClassName("neirong");

for (var i = 0; i < aButton.length; i++) {
aButton[i].index=i;
aButton[i].onclick = function () {

for (var j = 0; j < aButton.length; j++) {
aButton[j].className = 'qiehuan '; // 注意空格不能少
aContent[j].className = 'neirong ';
}
this.className += 'actived';
aContent[this.index].className += 'show';
};
}
</script>