window.myPlugin = window.myPlugin || {};

window.myPlugin.showMsg = (function () {
  var mongolia, //蒙層
    promptBox, //提示框
    closeSpan, //關(guān)閉按鈕
    titleSpan, //提示標(biāo)題
    contextSpan, //提示信息
    okBtn, //確定按鈕
    cancelBtn, //取消按鈕
    isRegEvent, //是否注冊(cè)事件
    option; //傳入的參數(shù)



  /**
   * 初始化蒙層
   */
  function initMongolia() {
    if (!mongolia) { //沒有蒙層則初始化
      //蒙層：覆蓋整個(gè)窗口，半透明的黑色
      mongolia = document.createElement("div");
      mongolia.style.position = "fixed";
      mongolia.style.width = mongolia.style.height = "100%";
      mongolia.style.left = mongolia.style.top = 0;
      mongolia.style.background = "rgba(0,0,0,.5)";
      document.body.appendChild(mongolia);
    }
    mongolia.style.display = "block"; //展示蒙層
  }

  /**
   * 初始化提示框
   */
  function initPromptBox() {
    //提示框：寬高300，位置居中
    if (!promptBox) {
      promptBox = document.createElement("div");
      promptBox.style.width = promptBox.style.height = "300px";
      promptBox.style.background = "#fff";
      promptBox.style.fontSize = "14px";
      promptBox.style.position = "absolute";
      promptBox.style.top = promptBox.style.left = "50%";
      promptBox.style.marginLeft = promptBox.style.marginTop = "-150px";
      promptBox.style["data-myplugin-id"] = "promptBox";
      initPromptContext();
      mongolia.appendChild(promptBox);
      titleSpan = document.querySelector("[data-myplugin-id='title']"); //提示標(biāo)題
      contextSpan = document.querySelector("[data-myplugin-id='message']"); //提示信息
      closeSpan = document.querySelector("[data-myplugin-id='close']"); //關(guān)閉按鈕
      okBtn = document.querySelector("[data-myplugin-id='ok']"); //確定按鈕
      cancelBtn = document.querySelector("[data-myplugin-id='cancel']"); //取消按鈕
    }

    okBtn.innerText = option.okText || "確定";
    cancelBtn.innerText = option.cancelText || "取消";
    titleSpan.innerText = option.title || "提示";
    contextSpan.innerText = option.context || "";
  }

  /**
   * 初始化提示框中的內(nèi)容
   */
  function initPromptContext() {
    //內(nèi)容包含：標(biāo)題，關(guān)閉按鈕，提示信息，確定按鈕，取消按鈕

    //創(chuàng)建標(biāo)題，關(guān)閉按鈕
    var div = document.createElement("div");
    div.innerHTML = `<span style="float:left;" data-myplugin-id="title"></span>
    <span style="float:right;cursor:pointer;" data-myplugin-id="close">X</span>`;
    div.style.height = "50px";
    div.style.padding = "10px 20px";
    div.style.background = "#eee";
    div.style.boxSizing = "border-box";
    promptBox.appendChild(div);

    //創(chuàng)建提示信息
    div = document.createElement("div");
    div.innerHTML = `<span data-myplugin-id="message"></span>`;
    div.style.height = "200px";
    div.style.padding = "10px 20px";
    div.style.boxSizing = "border-box";
    promptBox.appendChild(div);

    //創(chuàng)建確定按鈕，取消按鈕
    div = document.createElement("div");
    div.innerHTML = `<button style="float:right;margin:10px;cursor:pointer;" data-myplugin-id="cancel"></button><button style="float:right;margin:10px;cursor:pointer;" data-myplugin-id="ok"></button>`;
    div.style.height = "50px";
    div.style.padding = "10px 20px";
    div.style.boxSizing = "border-box";
    promptBox.appendChild(div);
  }

  //注冊(cè)事件
  function regEvent() {
    if (!isRegEvent) { //未注冊(cè)事件
      //1.點(diǎn)擊關(guān)閉，點(diǎn)擊蒙層，點(diǎn)擊取消按鈕
      closeSpan.onclick = mongolia.onclick = function () {
        mongolia.style.display = "none"; //隱藏蒙層
      };

      okBtn.onclick = function () {
        option && option.okFunction && option.okFunction();
        mongolia.style.display = "none"; //隱藏蒙層
      }

      cancelBtn.onclick = function () {
        option && option.cancelFunction && option.cancelFunction();
        mongolia.style.display = "none"; //隱藏蒙層
      }

      //2.拖動(dòng)提示框事件
      window.onmousedown = function (e) {
        var target = getTarget(e.target); //是否包含目標(biāo)元素

        if (target) {
          var style = window.getComputedStyle(target);
          var left = parseInt(style.left);
          var top = parseInt(style.top);
          var disX = parseInt(e.pageX) - left;
          var disY = parseInt(e.pageY) - top;

          window.onmousemove = function (e) {
            var newLeft = parseInt(e.pageX) - disX;
            var newTop = parseInt(e.pageY) - disY;

            promptBox.style.left = newLeft + "px";
            promptBox.style.top = newTop + "px";

          };
          window.onmouseup = window.onmouseleave = function () {
            window.onmousemove = null;
          }
        }
      };

      function getTarget(target) {
        while (target) {
          if (target.tagName === "DIV" && target.style["data-myplugin-id"] === "promptBox") {
            return target;
          } else {
            target = target.parentElement;
          }
        }
        return false;
      }
    }
  }




  /**
   * @param {object} opts 
   * opts.title : 提示標(biāo)題
   * opts.context : 提示信息
   * opts.cancelText:取消按鈕內(nèi)容
   * opts.okText:確定按鈕內(nèi)容
   * opts.cancelText:取消按鈕內(nèi)容
   * opts.okFunction:確定按鈕的回調(diào)函數(shù)
   * opts.cancelFunction:取消按鈕的回調(diào)函數(shù)
   */
  function showMsg(opts) {
    if (typeof opts === "string") {
      option = {
        context: opts
      }
    } else {
      option = opts || {};
    }
    initMongolia();
    initPromptBox();
    regEvent();
  }

  return showMsg;
}());

myPlugin.js

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script src="./js/myPlugin.js"></script>
  <script>
    window.myPlugin.showMsg({
      title: "信息",
      context: "確定刪除嗎",
      okText: "OK",
      cancelText: "Cancel",
      okFunction: function(){
        console.log("點(diǎn)擊OK按鈕");
      },
      cancelFunction:function(){
        console.log("點(diǎn)擊Cancel按鈕");
      }
    });
  </script>
</body>

</html>

index.html