javascript - 修改 JavaScript 中的排序函数

Question

谁能解释一下下面的代码:

var values = [213, 16, 2058, 54, 10, 1965, 57, 9];
values.sort(function(value1,value2){ return value2 - value1; });

我无法理解 value1 和 value2 是如何从数组值中加载的，以及它如何反转排序结果。

Answer 1

排序函数执行以下操作:

return value2 - value1;

让我们让它更详细一点，这样我们就可以看到发生了什么:

var values = [213, 16, 2058, 54, 10, 1965, 57, 9];
values.sort(function(value1,value2){ 
    console.log(value2 + ' - ' + value1 + ' = ' + (value2 - value1) + ' | (' + (value2 - value1 > 0 ? 'positive | ' + value2 + ' should be before ' + value1 : 'negative | ' + value2 + ' should be after ' + value1) + ')'); 

    return value2 - value1; 
});

输出:

  16 -  213 = -197 | (negative | 16 should be after 213)
2058 -   16 = 2042 | (positive | 2058 should be before 16)
2058 -  213 = 1845 | (positive | 2058 should be before 213)
  54 -   16 =   38 | (positive | 54 should be before 16)
  54 -  213 = -159 | (negative | 54 should be after 213)
  10 -   16 =   -6 | (negative | 10 should be after 16)
1965 -   10 = 1955 | (positive | 1965 should be before 10)
1965 -   16 = 1949 | (positive | 1965 should be before 16)
1965 -   54 = 1911 | (positive | 1965 should be before 54)
1965 -  213 = 1752 | (positive | 1965 should be before 213)
1965 - 2058 =  -93 | (negative | 1965 should be after 2058)
  57 -   10 =   47 | (positive | 57 should be before 10)
  57 -   16 =   41 | (positive | 57 should be before 16)
  57 -   54 =    3 | (positive | 57 should be before 54)
  57 -  213 = -156 | (negative | 57 should be after 213)
   9  -  10 =   -1 | (negative | 9 should be after 10) 

如果对所有值执行以下操作，您会注意到如果 value2 大于 value1，结果将始终为正，并且会向前移动在数组中 - 基本上以反向排序的数组结束。