js知识点

Dear 丶 2022-11-09 12:53 239阅读 0赞

## (1).js-Map集合 ##

//js创建map对象
    var map = new Map();
    //将键值对放入map对象
    map.set("key",value)
    map.set("key1",value1)
    map.set("key2",value2)
    //根据key获取map值
    map.get(key)
    //删除map指定对象
    delete map[key]或map.delete(key)
    //循环遍历map -> 输出的是map中的value值
    map.forEach(function(key){ 　console.log("key",key)  })

## (2).js-undefined 、null判断 ##

var exp = undefined;
    if (typeof exp == "undefined"){     alert("undefined");}
    
    var exp = null;
    if (!exp && typeof exp != "undefined" && exp != 0)
    {   alert("is null");}

## (3).js- ajax Map集合遍历 ##

$.ajax({ 
      type: "get",
      url: ctx + "index/mapgis/data/"+id,
      async: true, //异步
      dataType:'json', 
      success: function (json) { 
    	var mapList = json.data.mapList;
    	for(var key in mapList){    
       		var keyVauel = key;  //key值
       		var list = mapList[keyVauel];  //val值
       		//list集合遍历
       		for(var i=0;i<list.length;i++){ 
       		  var  user = list[i];
       		  var name = user.name;
       		  var id= user.id;
       		}
        }
       } 
    });

## (4).js- select中change事件，取消下拉框、选择值 ##

/* <select name="typeid" id="maptype3" class="form-control m-b"> <option value="0" selected="selected">--请选择--</option> </select> */
    $('#typeid').on('change',function(){   //change事件触发
    	var val =  $("#maptype3").val();  //select选择值
    	$("#maptype3").val("0");           //select设置默认值
    	$("#maptype3").prop("disabled", true);  //取消select下拉框 
    });

## (5).js-数组添加和删除 ##

var  ary = new Array();
    ary.push("c");  //添加
    ary.splice(parent.snos.indexOf("c"),1);  //指定元素删除

## (6).js-父子窗口交互(Layui) ##

//(1)父窗口
            var  mid = "";
            var  mname = "";
            function mineStation(mineID,mineName) { 
            	mid = mineID;
            	mname = mineName;
                layer.open({ 
                    type: 2,
                    title: [mineName,'cursor: move; background: #f3f3f4; font-weight: 900;'],
                    maxmin: true,
                    shadeClose: false, // 点击遮罩关闭层
                    area: [($(window).width()) + "px", ($(window).height()) + "px"],
                    content: "/used/mineStation?mineID=" + mineID,
                    success: function(layer, index){ 
                    	   //2.调用子窗口函数## 
                    	   var num = window["layui-layer-iframe"+index].callbackdata1();
                    	   //3.标题回显分站信息## 
                    	   $(".layui-layer-title")[0].innerText= mineName+"("+num+")";  
                    }
                });
            }
    //(2)子窗口
       var num = '[[${num}]]';
       function callbackdata1(){ 
          //1.调用父窗口变量和函数## 
       	  var mineID =  parent.mid;  
    	  return num;
       }