过滤阵列数组以仅保留每个ID最新日期的元素

Question

如何过滤此数组

    var arr = [[1, "3/20/2018", "A"], [1, "3/20/2018", "B"], 
               [1, "4/20/2018", "A"], [1, "4/20/2018", "B"], 
               [2, "1/30/2018", "A"], [2, "1/30/2018", "B"], 
               [2, "3/30/2018", "A"], [2, "3/30/2018", "B"]
              ];

我想过滤每个其他子元素（ID）的最新日期元素。要获得此输出：

var result = [[1, "4/20/2018", "A"], [1, "4/20/2018", "B"],
              [2, "3/30/2018", "A"], [2, "3/30/2018", "B"]
             ];

Answer 1

一些观察/假设

1. 日期3/20/2018附近缺少引号。没有引号，这只是一个浮点数
2. 您的子阵列有3个项目，其中第一个和最后一个项目形成唯一的组合（ID）。

基于以上所述，您可以尝试以下

＆＃13;
＆＃13;
var arr = [[1, "3/20/2018", "A"], [1, "3/20/2018", "B"], [1, "4/20/2018", "A"], [1, "4/20/2018", "B"], [2, "1/30/2018", "A"], [2, "1/30/2018", "B"], [2, "3/30/2018", "A"], [2, "3/30/2018", "B"]];
             
   var obj = {};
   
   arr.forEach(function(item){
     var id = item[0] + "_" + item[2];
     if(obj[id]) {
       if(new Date(item[1]) > new Date(obj[id][1])) {
          obj[id] = item;  
       }
     } else {
       obj[id] = item;
     }
  });
   
  console.log(Object.values(obj));
＆＃13;
＆＃13;
＆＃13;