form.val() 赋值 radio 的值为布尔值时无法赋值问题. (#1903)

Co-authored-by: meihangbo <meihangbo@126.com>

src/modules/form.js

@@ -117,7 +117,7 @@ layui.define(['lay', 'layer', 'util'], function(exports){
           itemElem[0].checked = value;
         } else if(type === 'radio') { // 如果为单选框
           itemElem.each(function(){
-            this.checked = this.value == value;
+            this.checked = this.value == value + '';
           });
         } else { // 其它类型的表单
           itemElem.val(value);