Question

我正在尝试在JS中对对象进行排序，但sort函数似乎对我的对象不起作用。

我想按频率对数组进行排序，降序。

["B", "A", "C", "C", "A"]将导致[C: 2, A: 2, B: 1]

var arr = ["B", "A", "C", "C", "A"];
var arrFrequency = [];

arr.forEach(function(value) {
  arrFrequency[value] = 0;
});

console.log(arrFrequency);
// [B: 0, A: 0, C: 0] 

arr.filter(function(value) {
  if (arrFrequency.hasOwnProperty(value)) arrFrequency[value]++;
});

console.log(arrFrequency);
// [B: 1, A: 2, C: 2]

Answer 1

对象没有任何已定义的订单。但是，您可以先创建一个这样的对象：

var arr = ["B", "A", "C", "C", "A"];
var freq = {};
arr.forEach(function(value) {
    freq[value] = (freq[value] || 0) + 1;
});
console.log(freq); // {B: 1, A: 2, C: 2}

然后将此对象的键映射到数组：

var arrFrequency = [];
for(var k in freq) {
    arrFrequency.push({ key: k, count: freq[k] });
};
console.log(arrFrequency); // [{"key":"B","count":1},{"key":"A","count":2},{"key":"C","count":2}]

现在就这样排序：

arrFrequency.sort(function(x, y) {
    return y.count - x.count;
});
console.log(arrFrequency); // [{"key":"A","count":2},{"key":"C","count":2},{"key":"B","count":1}]

Demonstration

Answer 2

我的这种排序功能可以帮助您：

 // sort objects according to their key-names (a,b,c):

 function sortObjArray(array){
    for(var k=1; k < array.length; k++){
      for(var i=k; i > 0; i--){
        var formerLetter = Object.keys(array[i-1]);
        var currLetter = Object.keys(array[i]);
        if( currLetter < formerLetter ){
          [x,y] = [array[i],array[i-1]];
          [array[i],array[i-1]] = [y,x];
        }
      }
    }
    return array;
 }

 var array = [{ b: 4},{ c: 1},{ a: 3}];
 sortObjArray(array);//[Object { a=3}, Object { b=4}, Object { c=1}]


 // or in descending order, according to their occurrence

 function sortObjArray2(array){
    for(var k=1; k < array.length; k++){
       for(var i=k; i > 0; i--){
          var formerLetter = Object.keys(array[i-1])[0];
          var currLetter = Object.keys(array[i])[0];

          var formerValue = array[i-1][formerLetter]; 
          var currValue = array[i][currLetter];

          if( currValue> formerValue ){
            [x,y] = [array[i],array[i-1]];
            [array[i],array[i-1]] = [y,x];
          }
       }
     }
     return array;
  }

  var array = [{ b: 4},{ c: 1},{ a: 3}];
  sortObjArray2(array);//[Object { b=4}, Object { a=3}, Object { c=1}]

排序功能对对象不起作用

2 个答案: