取<%= %>变量时获取String类型
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username.aspx.cs文件中设置了一个public的String类型的值
public int number = 1;
public string username = "zww";
username.aspx文件js
<script>
var number= <%=number%>; //number为1，输出正常√
var username = '<%=username%>'; //username为'zww',输出正常√
var username = <%=username%>; //username为zww，报错（zww is not defined）,zww为一个变量
</script>
