JS 驗證碼功能的三種實現方式

<input type="text" name="phone" id="phone" value="" placeholder="請輸入手機號" maxlength="11" />
<input type="" name="verCode" id="verCode" value="" placeholder="請輸入驗證碼" maxlength="6"/>
<input type="button" name="" id="verCodeBtn" value="獲取驗證碼" onclick="settime(this);"/>

//驗證碼
var counts = 60;

function settime(val) {
 if(counts == 0) {
 val.removeAttribute("disabled");
 val.value = "獲取驗證碼";
 counts = 60;
 return false;
 } else {
 val.setAttribute("disabled", true);
 val.value = "重新發送（" + counts + "）";
 counts--;
 }
 setTimeout(function() {
 settime(val);
 }, 1000);
}

$(function(){
 //獲取驗證碼
 $("#verCodeBtn").click(function() {
 var userinfo = {
 "UserPhoneNum": '86//' + $("input[name='phone']").val()
 }
 $.ajax({
 url: "https://www.xxxxx.cn/user/sendcode/",
 data: userinfo,
 type: "get",
 success: function(data) {
 if(JSON.parse(data).state === 404 || JSON.parse(data).state === 202 || userinfo.UserPhoneNum === '86//') {
 alert("驗證碼發送失敗")
 } else {
 alert("驗證碼發送成功，請耐心等待")
 }
 },
 error: function() {
 alert("發送失敗");
 }
 });
 });
})

<div class="code">
 <input type="text" value="" placeholder="請輸入驗證碼（不區分大小寫）" class="input-val">
 <canvas id="canvas" width="100" height="30"></canvas>
 <button class="btn">提交</button>
 </div>

<style>
 .input-val {
 width: 200px;
 height: 32px;
 border: 1px solid #ddd;
 box-sizing: border-box;
 }
 #canvas {
 vertical-align: middle;
 box-sizing: border-box;
 border: 1px solid #ddd;
 cursor: pointer;
 }
 .btn {
 display: block;
 margin-top: 20px;
 height: 32px;
 width: 100px;
 font-size: 16px;
 color: #fff;
 background-color: #457adb;
 border: none;
 border-radius: 50px;
 }
 </style>

<script type="text/javascript" src="js/jquery-3.3.1.min.js" ></script>
<script>
 $(function(){
 var show_num = [];
 draw(show_num);
 $("#canvas").on('click',function(){
 draw(show_num);
 })
 $(".btn").on('click',function(){
 var val = $(".input-val").val().toLowerCase();
 var num = show_num.join("");
 if(val==''){
 alert('請輸入驗證碼！');
 }else if(val == num){
 alert('提交成功！');
 $(".input-val").val('');
 // draw(show_num);
 }else{
 alert('驗證碼錯誤！請重新輸入！');
 $(".input-val").val('');
 // draw(show_num);
 }
 })
 })
 //生成并渲染出驗證碼圖形
 function draw(show_num) {
 var canvas_width=$('#canvas').width();
 var canvas_height=$('#canvas').height();
 var canvas = document.getElementById("canvas");//獲取到canvas的對象，演員
 var context = canvas.getContext("2d");//獲取到canvas畫圖的環境，演員表演的舞臺
 canvas.width = canvas_width;
 canvas.height = canvas_height;
 var sCode = "a,b,c,d,e,f,g,h,i,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z,A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0";
 var aCode = sCode.split(",");
 var aLength = aCode.length;//獲取到數組的長度
 for (var i = 0; i < 4; i++) { //這里的for循環可以控制驗證碼位數（如果想顯示6位數，4改成6即可）
 var j = Math.floor(Math.random() * aLength);//獲取到隨機的索引值
 // var deg = Math.random() * 30 * Math.PI / 180;//產生0~30之間的隨機弧度
 var deg = Math.random() - 0.5; //產生一個隨機弧度
 var txt = aCode[j];//得到隨機的一個內容
 show_num[i] = txt.toLowerCase();
 var x = 10 + i * 20;//文字在canvas上的x坐標
 var y = 20 + Math.random() * 8;//文字在canvas上的y坐標
 context.font = "bold 23px 微軟雅黑";
 context.translate(x, y);
 context.rotate(deg);
 context.fillStyle = randomColor();
 context.fillText(txt, 0, 0);
 context.rotate(-deg);
 context.translate(-x, -y);
 }
 for (var i = 0; i <= 5; i++) { //驗證碼上顯示線條
 context.strokeStyle = randomColor();
 context.beginPath();
 context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height);
 context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height);
 context.stroke();
 }
 for (var i = 0; i <= 30; i++) { //驗證碼上顯示小點
 context.strokeStyle = randomColor();
 context.beginPath();
 var x = Math.random() * canvas_width;
 var y = Math.random() * canvas_height;
 context.moveTo(x, y);
 context.lineTo(x + 1, y + 1);
 context.stroke();
 }
 }
 //得到隨機的顏色值
 function randomColor() {
 var r = Math.floor(Math.random() * 256);
 var g = Math.floor(Math.random() * 256);
 var b = Math.floor(Math.random() * 256);
 return "rgb(" + r + "," + g + "," + b + ")";
 }
</script>

<div class="drag">
 <div class="bg"></div>
 <div class="text" onselectstart="return false;">請拖動滑塊解鎖</div>
 <div class="btn">>></div>
</div>

<style>
 .drag{
 width: 300px;
 height: 40px;
 line-height: 40px;
 background-color: #e8e8e8;
 position: relative;
 margin:0 auto;
 }
 .bg{
 width:40px;
 height: 100%;
 position: absolute;
 background-color: #75CDF9;
 }
 .text{
 position: absolute;
 width: 100%;
 height: 100%;
 text-align: center;
 user-select: none;
 }
 .btn{
 width:40px;
 height: 38px;
 position: absolute;
 border:1px solid #ccc;
 cursor: move;
 font-family: "宋體";
 text-align: center;
 background-color: #fff;
 user-select: none;
 color:#666;
 }
</style>

<script>
 //一、定義一個獲取DOM元素的方法
 var $ = function(selector){
 return document.querySelector(selector);
 },
 box = $(".drag"),//容器
 bg = $(".bg"),//背景
 text = $(".text"),//文字
 btn = $(".btn"),//滑塊
 success = false,//是否通過驗證的標志
 distance = box.offsetWidth - btn.offsetWidth;//滑動成功的寬度（距離）
 //二、給滑塊注冊鼠標按下事件
 btn.onmousedown = function(e){
 //1.鼠標按下之前必須清除掉后面設置的過渡屬性
 btn.style.transition = "";
 bg.style.transition ="";
 //說明：clientX 事件屬性會返回當事件被觸發時，鼠標指針向對于瀏覽器頁面(或客戶區)的水平坐標。
 //2.當滑塊位于初始位置時，得到鼠標按下時的水平位置
 var e = e || window.event;
 var downX = e.clientX;
 //三、給文檔注冊鼠標移動事件
 document.onmousemove = function(e){
 var e = e || window.event;
 //1.獲取鼠標移動后的水平位置
 var moveX = e.clientX;
 //2.得到鼠標水平位置的偏移量（鼠標移動時的位置 - 鼠標按下時的位置）
 var offsetX = moveX - downX;
 //3.在這里判斷一下：鼠標水平移動的距離 與 滑動成功的距離 之間的關系
 if( offsetX > distance){
 offsetX = distance;//如果滑過了終點，就將它停留在終點位置
 }else if( offsetX < 0){
 offsetX = 0;//如果滑到了起點的左側，就將它重置為起點位置
 }
 //4.根據鼠標移動的距離來動態設置滑塊的偏移量和背景顏色的寬度
 btn.style.left = offsetX + "px";
 bg.style.width = offsetX + "px";
 //如果鼠標的水平移動距離 = 滑動成功的寬度
 if( offsetX == distance){
 //1.設置滑動成功后的樣式
 text.innerHTML = "驗證通過";
 text.style.color = "#fff";
 btn.innerHTML = "√";
 btn.style.color = "green";
 bg.style.backgroundColor = "lightgreen";
 //2.設置滑動成功后的狀態
 success = true;
 //成功后，清除掉鼠標按下事件和移動事件（因為移動時并不會涉及到鼠標松開事件）
 btn.onmousedown = null;
 document.onmousemove = null;
 //3.成功解鎖后的回調函數
 setTimeout(function(){
 alert('解鎖成功！');
 },100);
 }
 }
 //四、給文檔注冊鼠標松開事件
 document.onmouseup = function(e){
 //如果鼠標松開時，滑到了終點，則驗證通過
 if(success){
 return;
 }else{
 //反之，則將滑塊復位（設置了1s的屬性過渡效果）
 btn.style.left = 0;
 bg.style.width = 0;
 btn.style.transition = "left 1s ease";
 bg.style.transition = "width 1s ease";
 }
 //只要鼠標松開了，說明此時不需要拖動滑塊了，那么就清除鼠標移動和松開事件。
 document.onmousemove = null;
 document.onmouseup = null;
 }
 }
</script>