<!DOCTYPE html>action="form-action.php"搜索: type="search" id="mySearch" name="filter" requiredtype="submit"点击 "点我" 按钮查看在表单提交前搜索字段是否为必填字段。onclick="myFunction()"点我id="demo"function myFunction() {var x = document.getElementById("mySearch").required;document.getElementById("demo").innerHTML = x;}