javascript - 如何获取属性值的个数？

Question

我想把id的值赋值给class属性的值，然后判断类是否存在，但是怎么写呢？

var id = 2;
var div1 = ($("#div1").hasClass("'treegrid-parent-'+id"));

if (div1) {
   console.log("true");
} else {
   console.log("false");
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="div1" class="treegrid-parent-2">2</div>

Answer 1

你快到了;-)

var id = 2;
var div1 = ($("#div1").hasClass('treegrid-parent-' + id));

if (div1) {
   console.log("true");
} else {
   console.log("false");
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="div1" class="treegrid-parent-2">2</div>