点击注册的时候，渲染出来，验证码是自动获取出来的

html：

 <div class="div1">
        用户名<input type="text" id="yhm"><span id="span1"></span><br>
        密码<input type="password" id="mm"><span id="span2"></span><br>
        Email<input type="email" id="ema"><span id="span3"></span><br>
        手机号<input type="text" id="sjh"><span id="span4"></span><br>
        验证码<input type="text" id="yzm" maxlength="4"><span id="span5"></span><br>
        <button id="btn">注册</button>
    </div>
    <p id="p1"></p>

script：

<script>
        // 用户名验证
        document.getElementById("yhm").addEventListener("blur", function () {
            var username = this.value;
            var spanElement = document.getElementById("span1");
            var usernameRegex = /^[a-zA-Z0-9]{3,6}$/;

            if (usernameRegex.test(username)) {
                spanElement.innerHTML = '√';
            } else {
                spanElement.innerHTML = '×';
            }
        });

        // 密码验证
        document.getElementById("mm").addEventListener("blur", function () {
            var password = this.value;
            var spanElement = document.getElementById("span2");

            if (password.length >= 6 && password.length <= 16) {
                spanElement.innerHTML = '√';
            } else {
                spanElement.innerHTML = '×';
            }
        });

        // Email验证
        document.getElementById("ema").addEventListener("blur", function () {
            var email = this.value;
            var spanElement = document.getElementById("span3");
            var emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;

            if (emailRegex.test(email)) {
                spanElement.innerHTML = '√';
            } else {
                spanElement.innerHTML = '×';
            }
        });

        // 手机号验证
        document.getElementById("sjh").addEventListener("blur", function () {
            var phoneNumber = this.value;
            var spanElement = document.getElementById("span4");
            var phoneRegex = /^1\d{10}$/;

            if (phoneRegex.test(phoneNumber)) {
                spanElement.innerHTML = '√';
            } else {
                spanElement.innerHTML = '×';
            }
        });
        // 生成验证码
        function generateCaptcha() {
            var captcha = "";
            var characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
            for (var i = 0; i < 4; i++) {
                captcha += characters.charAt(Math.floor(Math.random() * characters.length));
            }
            return captcha;
        }

        // 显示验证码
        document.getElementById("yzm").value = generateCaptcha();

        // 注册按钮点击事件
        document.getElementById("btn").addEventListener("click", function () {
            var p1Element = document.getElementById("p1");
            var yhmInput = document.getElementById("yhm").value;
            var mmInput = document.getElementById("mm").value;
            var emaInput = document.getElementById("ema").value;
            var sjhInput = document.getElementById("sjh").value;
            var yzmInput = document.getElementById("yzm").value;

            p1Element.innerHTML = "用户名：" + yhmInput + "<br>" +
                "密码：" + mmInput + "<br>" +
                "Email：" + emaInput + "<br>" +
                "手机号：" + sjhInput + "<br>" +
                "验证码：" + yzmInput;
        });