数组内的最高计数循环

Question

在此示例中，如何通过层次排序（1. 306，2. 267，3. 263）获取最大3个值的列表或数组？

var array = [267, 306, 108, 263, 67]; 
var largest = Math.max.apply(Math, array); // 306 

Answer 1

您需要从最大到最小排序，然后切分前三项。

var arr = [267, 306, 108, 263, 67]; 
 

 
console.log(arr.sort((a, b) => b - a).slice(0, 3));

.as-console-wrapper { top: 0; max-height: 100% !important; }

Answer 2

您可以使用Array.sort() 和Array.slice() 方法来得到你想要的。

var array = [267, 306, 108, 263, 67]; 
var sorted = array.sort(function(a,b) { return b - a }); // sort the array in descending order 
var largest = sorted.slice(0, 3); // get first three array elements 
console.log(largest); // Array [ 306, 267, 263 ] 

Answer 3

你可以把它想：

var array = [267, 306, 108, 263, 67]; 

findLargest3(); 

function findLargest3(){ 
    // sort descending 
    array.sort(function(a,b){ 
     if(a < b){ return 1; } 
     else if(a == b) { return 0; } 
     else { return -1; } 
    }); 
    alert(array.slice(0, 3)); 

} 

工作Js Fiddle

Answer 4

你可以写一个辅助函数，就像这样：

function getTopItems(arr, howMany, comparator) { 
    if (typeof comparator !== "function") { 
     comparator = function(a, b) {return a > b;}; 
    } 
    function addToOutput(item) { 
     var previous = item; 
     var found = false; 
     for (var innerIndex = 0; innerIndex < output.length; innerIndex++) { 
      if (found) { 
       var aux = previous; 
       previous = output[innerIndex]; 
       output[innerIndex] = aux; 
      } else if (comparator(item, output[innerIndex])) { 
       found = true; 
       var aux = previous; 
       previous = output[innerIndex]; 
       output[innerIndex] = aux; 
      } 
      console.log(output); 
     } 
     if (output.length < howMany) output.push(previous); 
    } 
    var index = 0; 
    var output = []; 
    while (index < arr.length) { 
     addToOutput(arr[index++]); 
    } 
    return output; 
}