js筛选数组中相同的成为新数组

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title></title>
</head>
<body>
<script>
var college = [
	{num:1,lastName:'赵大'},
	{num:1,lastName:'赵二'},
	{num:3,lastName:'钱三'},
	{num:3,lastName:'钱四'},
	{num:1,lastName:'孙五'},
	{num:1,lastName:'孙六'},
	{num:2,lastName:'李七'},
	{num:2,lastName:'李八'},
	{num:1,lastName:'孙六'}
];

//先用map结构记录
function arrayToMap(data) {
  //非数组或数据长度为0不处理
  if(!data instanceof Array || data.length == 0) {
    return {};
  }
  var map = {};
  for(var i=0;i<data.length;i++) {
    if(!data[i] instanceof Array || data.length < 2) {
      continue;
    }

    let name = data[i].num;
    if(name != undefined) {
      if(map[name] == undefined) {
        map[name] = [];
      }
      map[name].push(data[i]);
    }
  }
  return map;
}

//把map转成数组
function mapToArray(data) {
  if(data == undefined) {
    return [];
  }
  let array = [];
  for(let p in data) {
    array.push(data[p]);
  }
  return array;
}

//测试
var map = arrayToMap(college);
var array = mapToArray(map);
console.log(map)
console.log(array)
</script>
</body>
</html>

在这里插入图片描述

原文链接：https://blog.csdn.net/Guoyu1_/article/details/117367579