<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>Document</title><style>.box{width: 400px;margin: 50px auto;border: 1px solid #ccc;padding: 50px;}#phone{text-align: center;margin-bottom: 20px;border: 1px solid #ccc;color: #333;}.submit,.disable,#phone{display: block;width: 190px;height: 35px;border-radius: 5px;margin-left:auto;margin-right:auto;}.disable{border: none;background-color: #ccc;color: #fff;}.submit{border: none;background-color: red;color: #fff;}</style></head><body><div class="box"><input id="phone" type="text" placeholder="输入领券手机号" maxlength="11"><button id="submit" class="disable" disabled>确认领取</button></div><script src="jquery.min.js"></script><script>$(function () {var $phone = $("#phone");var $submit = $("#submit");$phone.on("input propertychange", function () {var phone = this.value;if (/^((13[0-9]|15[0-9]|17[0-9]|18[0-9])+d{8})$/.test(phone)) {$submit.removeClass("disable").addClass("submit").removeAttr("disabled");} else {$submit.removeClass("submit").addClass("disable").attr("disabled", "disabled");}});});</script></body></html> 效果:
用户输入的手机号符合规则时:

ps:jquery验证电话号码
var isMobile=/^(?:13d|15d|18d)d{5}(d{3}|*{3})$/; //手机号码验证规则var isPhone=/^((0d{2,3})-)?(d{7,8})(-(d{3,}))?$/;//座机验证规则var dianhua = $("#dianhua").val();//获得用户填写的号码值 赋值给变量dianhuaif(!isMobile.test(dianhua) && !isPhone.test(dianhua)){ //如果用户输入的值不同时满足手机号和座机号的正则alert("请正确填写电话号码,例如:13415764179或0321-4816048"); //就弹出提示信息$("#dianhua").focus();//输入框获得光标return false; //返回一个错误,不向下执行