Count the number of occurrences of repeated elements in JavaScript

The editor below will share with you an example of deduplicating a JavaScript array and counting the number of occurrences of repeated elements. It has a good reference value and I hope it will be helpful to everyone. Let’s follow the editor and take a look.

1. Method one

var arr = [1, 2, 3, 1, 2, 4];
  function arrayCnt(arr) {
  var newArr = [];
  for(var i = 0; i < arr.length; i++) {
   if(newArr.indexOf(arr[i]) == -1) {
   newArr.push(arr[i])
   }
  }
  var newarr2 = new Array(newArr.length);
  for(var t = 0; t < newarr2.length; t++) {
   newarr2[t] = 0;
  }
  for(var p = 0; p < newArr.length; p++) {
   for(var j = 0; j < arr.length; j++) {
   if(newArr[p] == arr[j]) {
    newarr2[p]++;
   }
   }
  }
  for(var m = 0; m < newArr.length; m++) {
   console.log(newArr[m] + "重复的次数为：" + newarr2[m]);
  }
  }
  arrayCnt(arr);

2. Method two (set method Remove duplicates)

var arr = [1, 2, 3, 1, 2, 4];
  function arrayCnt(arr) {
  var newArr = [];
  //使用set进行数组去重
  newArr = [...new Set(arr)];
  var newarr2 = new Array(newArr.length);
  for(var t = 0; t < newarr2.length; t++) {
   newarr2[t] = 0;
  }
  for(var p = 0; p < newArr.length; p++) {
   for(var j = 0; j < arr.length; j++) {
   if(newArr[p] == arr[j]) {
    newarr2[p]++;
   }
   }
  }
  for(var m = 0; m < newArr.length; m++) {
   console.log(newArr[m] + "重复的次数为：" + newarr2[m]);
  }
  }
  arrayCnt(arr);

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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