本文實例講述了原生js實現的移動端可拖動進度條插件功能。分享給大家供大家參考，具體如下：
該插件最初的想法來自網上的一篇文章，直達鏈接：http://www.survivalescaperooms.com/kaifa/javascript/352204.html
筆者因為業務需要尋找到這個插件，然后拿來用之，發現各種不方便，然后便開始了改造之路。
上代碼：
<script> function dragSlide(id) { this.minDiv =document.getElementById(id); //小方塊 this.width = parseInt(window.getComputedStyle(this.minDiv, null).width); //小方塊的寬度 this.lineDiv = this.minDiv.parentNode; //長線條 //滑動的數值呈現 this.vals = this.minDiv.children[0]; var that=this; var move = function(e) { var x = e.touches[0].pageX; var lineDiv_left = that.getPosition(that.lineDiv).left; //長線條的橫坐標 var minDiv_left = x - lineDiv_left; //小方塊相對于父元素（長線條）的left值 if (minDiv_left >= that.lineDiv.offsetWidth - that.width) { minDiv_left = that.lineDiv.offsetWidth - that.width; } if (minDiv_left <0 ) { minDiv_left = 0; } //設置拖動后小方塊的left值 that.minDiv.style.left = minDiv_left + "px"; //percent百分比改為如下所示,解決開始和最后滑動的體驗不好問題 var percent = (minDiv_left / (that.lineDiv.offsetWidth - that.width)) * 100; if (percent > 0 && percent < 0.5) { percent = Math.ceil(percent); } else { percent = Math.floor(percent); } that.vals.innerText = percent; } //獲取元素的絕對位置,工具函數 this.getPosition = function(node) { var left = node.offsetLeft; //獲取元素相對于其父元素的left值var left var top = node.offsetTop; current = node.offsetParent; // 取得元素的offsetParent // 一直循環直到根元素 while (current != null) { left += current.offsetLeft; top += current.offsetTop; current = current.offsetParent; } return { "left": left, "top": top }; } this.minDiv.addEventListener("touchmove", move); } var drag0 = new dragSlide("minDiv"); var drag1 = new dragSlide("minDiv1"); //取消移動端手勢長按彈出提示框的操作 document.addEventListener('contextmenu', function(e) { e.preventDefault(); });</script>html和css部分沒有改動，而js改動還是很大的，比較原來作者的文章，改動點如下
1）整體上，原來不是插件，改造之后成為一個可以復用的插件，雖然簡單了點
2）只是將其改造為適用于移動端的插件
3）通過對開始滑動和結束滑動比例的處理，優化了開始滑動和結束滑動的體驗
4）移動端加了防止長按彈出提示框的代碼
5）小滑塊的寬度改為動態
改造之后的整體案例，需要指出：筆者主要用在微信端，至于其他瀏覽器滑塊的體驗不是很好，還有滑塊滑動體驗跟小塊的尺寸有直接關系。
<!DOCTYPE html><html lang="zh-cn"><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <meta name="viewport" content="width=device-width,initial-scale=1,maximum-scale=1,user-scalable=no" /> <title>鼠標拖動小方塊</title> <style type="text/css"> .lineDiv { position: relative; height: 5px; background: red; width: 300px; margin: 50px auto; } .lineDiv .minDiv { position: absolute; top: -12.5px; left: 0; width: 30px; height: 30px; background: green; cursor: pointer } .lineDiv .minDiv .vals { position: absolute; font-size: 20px; top: -45px; left: -2.5px; width: 35px; height: 35px; line-height: 35px; text-align: center; background: blue; } .lineDiv .minDiv .vals:after { content: ""; width: 0px; height: 0px; border-top: 6px solid blue; border-left: 6px solid transparent; border-right: 6px solid transparent; border-bottom: 6px solid transparent; display: block; margin-left: 11px; } * { -webkit-user-select: none; -moz-user-select: none; -ms-user-select: none; user-select: none; } </style></head><body> <center> <h3>用鼠標拖動小方塊<span id="msg">0</span>%</h3> </center> <div id="lineDiv" class="lineDiv"> <div id="minDiv" class="minDiv"> <div id="vals" class="vals">0</div> </div> </div> <div style="height: 20px;"></div> <div id="lineDiv" class="lineDiv"> <div id="minDiv1" class="minDiv"> <div id="vals" class="vals">0</div> </div> </div> <script> //避免默認事件 2018.7.10 更新 優化uc瀏覽器左右滑動時候頁面被拖動 document.addEventListener('touchmove', function(e) { e.preventDefault(); }, { passive: false }); function dragSlide(id) { this.minDiv = document.getElementById(id); //小方塊 this.width = parseInt(window.getComputedStyle(this.minDiv, null).width); //小方塊的寬度 this.lineDiv = this.minDiv.parentNode; //長線條 //滑動的數值呈現 this.vals = this.minDiv.children[0]; var that = this; var lastX = null; //判斷鼠標移動方向，解決向左側滑動時候的bug var move = function(e) { var x = e.touches[0].pageX, direction = ''; if (lastX == null) { lastX = x; return; } if (x > lastX) { direction = 'right'; } else if (x < lastX) { direction = 'left'; } else { direction = ''; } var lineDiv_left = that.getPosition(that.lineDiv).left; //長線條的橫坐標 var minDiv_left = x - lineDiv_left; //小方塊相對于父元素（長線條）的left值 if (minDiv_left >= that.lineDiv.offsetWidth - that.width) { minDiv_left = that.lineDiv.offsetWidth - that.width; } if (minDiv_left < 0) { minDiv_left = 0; } //設置拖動后小方塊的left值 that.minDiv.style.left = minDiv_left + "px"; //percent百分比改為如下所示,解決開始和最后滑動的體驗不好問題 var percent = (minDiv_left / (that.lineDiv.offsetWidth - that.width)) * 100; if (percent < 0.5 && direction == 'right') { percent = Math.ceil(percent); } else if (percent > 0.5 && direction == 'right') { percent = Math.floor(percent); } else { percent = Math.ceil(percent); } that.vals.innerText = percent; } //獲取元素的絕對位置,工具函數 this.getPosition = function(node) { var left = node.offsetLeft; //獲取元素相對于其父元素的left值var left var top = node.offsetTop; current = node.offsetParent; // 取得元素的offsetParent // 一直循環直到根元素 while (current != null) { left += current.offsetLeft; top += current.offsetTop; current = current.offsetParent; } return { "left": left, "top": top }; } this.minDiv.addEventListener("touchmove", move); } var drag0 = new dragSlide("minDiv"); var drag1 = new dragSlide("minDiv1"); //取消移動端手勢長按彈出提示框的操作 document.addEventListener('contextmenu', function(e) { e.preventDefault(); }); </script></body></html>
希望本文所述對大家JavaScript程序設計有所幫助。
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