原生js实现一个自定义下拉单选选择框

  1 /* jshint esversion: 6 */
  2 (function (window, document) {
  3     let Selector = function (option) {
  4         //执行初始化方法，
  5         this._init(option);
  6     };
  7 
  8     Selector.prototype = {
  9         //初始化传入参数并定义初始化的相关变量
 10         _init({
 11             eleSelector = "", //传入的选择器 id,class，tag等，用于将选择框渲染到此选择器所在的元素
 12             options = [{
 13                 name: "请选择",
 14                 value: "0",
 15             }], //传入的下拉框对象，name为选择的文字，value为值
 16             defaultText = "请选择" //提供的默认选择的值
 17         }) {
 18             
 19             //将传入的数据绑定到this上
 20             this.parentEle = document.querySelector(eleSelector) || document.body; //要邦定的dom 
 21             this.options = options; //选择值数组对象
 22             this.defaultText = defaultText; //默认值
 23 
 24             this.dropboxShow = false; //定义存储下拉框的显示隐藏状态
 25             this.defaultValue = ""; //定义村赤默认选中的值
 26             this._creatElement(); //初始化后执行创建元素方法
 27         },
 28 
 29         //创建下拉选择框dom
 30         _creatElement() {
 31             //选择框最外层的包裹元素
 32             let wrapEle = document.createElement("div");
 33             wrapEle.className = "my-select";
 34 
 35             //根据传入的值获取选择框默认的值和内容
 36             this.options.forEach(item => {
 37                 if (item.name === "this.defaultText") {
 38                     this.defaultValue = item.value;
 39                 }
 40             });
 41 
 42             let selectWarpBox = document.createElement("div"); //选择框包裹元素
 43             selectWarpBox.className = "select-selection";
 44 
 45             let inputHideBox = document.createElement("input"); //隐藏保存选择值得元素
 46             inputHideBox.type = "hidden";
 47             inputHideBox.value = this.defaultValue;
 48 
 49             let selectShowBox = document.createElement("div"); //选择框默认展示框
 50             let selectNameBox = document.createElement("span"); //选择框展现的值ele
 51             selectNameBox.className = "select-selected-value";
 52             selectNameBox.id = "select-option";
 53             selectNameBox.innerText = this.defaultText; //将传入的默认值赋值
 54             let selectIcon = document.createElement("i"); //图标ele
 55             selectIcon.className = "arrow-down icon-select-arrow";
 56             //将span和角标添加到外层div
 57             selectShowBox.appendChild(selectNameBox);
 58             selectShowBox.appendChild(selectIcon);
 59 
 60             selectWarpBox.appendChild(inputHideBox);
 61             selectWarpBox.appendChild(selectShowBox);
 62 
 63             //下拉框
 64             let dropbox = document.createElement("div"),
 65                 ulbox = document.createElement("ul");
 66 
 67             dropbox.id = "select-drop";
 68             dropbox.className = "select-dropdown";
 69             ulbox.className = "select-dropdown-list";
 70             //遍历传入的选项数组对象，生成下拉菜单的li元素并赋值
 71             this.options.forEach((item) => {
 72                 let itemLi = document.createElement("li");
 73                 if (this.defaultText === item.name) {
 74                     itemLi.className = "select-item select-item-selected";
 75                 } else {
 76                     itemLi.className = "select-item";
 77                 }
 78 
 79                 itemLi.setAttribute("data-value", item.value);
 80                 itemLi.innerText = item.name;
 81                 ulbox.appendChild(itemLi);
 82 
 83             });
 84             //将下拉框ul推入到包裹元素
 85             dropbox.appendChild(ulbox);
 86 
 87             wrapEle.appendChild(selectWarpBox);
 88             wrapEle.appendChild(dropbox);
 89 
 90             this.parentEle.appendChild(wrapEle); //将生成的下拉框添加到所选元素中
 91 
 92             //把需要操作的dom挂载到当前实例
 93             //this.wrapEle = wrapEle;     //最外层包裹元素
 94             this.eleSelect = selectWarpBox; //选择框
 95             this.eleDrop = dropbox; //下拉框
 96             this.eleSpan = selectNameBox; //显示文字的span节点
 97 
 98             //绑定事件处理函数
 99             this._bind(this.parentEle);
100         },
101 
102         //点击下拉框事件处理函数
103         _selectHandleClick() {
104             if (this.dropboxShow) {
105                 this._selectDropup();
106             } else {
107                 this._selectDropdown();
108             }
109         },
110 
111         //收起下拉选项
112         _selectDropup() {
113             this.eleDrop.style.transform = "scale(1,0)";
114             this.eleDrop.style.opacity = "0";
115             this.eleSelect.className = "select-selection";
116             this.dropboxShow = false;
117         },
118 
119         //展示下拉选项
120         _selectDropdown() {
121             this.eleDrop.style.transform = "scale(1,1)";
122             this.eleDrop.style.opacity = "1";
123             this.eleSelect.className = "select-selection select-focus";
124             this.dropboxShow = true;
125         },
126 
127         //点击下拉选项进行赋值
128         _dropItemClick(ele) {
129             this.defaultValue = ele.getAttribute("data-value");
130             //document.querySelector("#select-value").value = ele.getAttribute("data-value");
131             this.eleSpan.innerText = ele.innerText;
132             ele.className = "select-item select-item-selected";
133             //对点击选中的其他所有兄弟元素修改class去除选中样式
134             this._siblingsDo(ele, function (ele) {
135                 if (ele) {
136                     ele.className = "select-item";
137                 }
138             });
139             this._selectDropup();
140         },
141 
142         //node遍历是否是子元素包裹元素
143         _getTargetNode(ele, target) {
144             //ele是内部元素，target是你想找到的包裹元素
145             if (!ele || ele === document) return false;
146             return ele === target ? true : this._getTargetNode(ele.parentNode, target);
147         },
148 
149         //兄弟元素遍历处理函数
150         _siblingsDo(ele, fn) {
151 
152             (function (ele) {
153                 fn(ele);
154                 if (ele && ele.previousSibling) {
155                     arguments.callee(ele.previousSibling);
156                 }
157             })(ele.previousSibling);
158 
159             (function (ele) {
160                 fn(ele);
161                 if (ele && ele.nextSibling) {
162                     arguments.callee(ele.nextSibling);
163                 }
164             })(ele.nextSibling);
165 
166         },
167 
168         //绑定下拉框事件处理函数
169         _bind(parentEle) {
170             let _this = this;
171             //事件委托到最外层包裹元素进行绑定处理
172             parentEle.addEventListener("click", function (e) {
173                 const ele = e.target;
174                 
175                 //遍历当前点击的元素，如果是选中框内的元素执行
176                 if (_this._getTargetNode(ele, _this.eleSelect)) {
177                     if (_this.dropboxShow) {
178                         _this._selectDropup();
179                     } else {
180                         _this._selectDropdown();
181                     }
182                 } else if (ele.className === "select-item") { //如果是点击的下拉框的选项执行
183                     _this._dropItemClick(ele);
184                 } else { //点击其他地方隐藏下拉框
185                     _this._selectDropup();
186                 }
187 
188             });
189 
190         }
191 
192     };
193     //将构造函数挂载到全局window
194     window.$Selector = Selector;
195 })(window, document);