计算数组中的重复项

Question

我试图显示我的数组的内容，但存在重复的地方只打印名称和数字，例如

myArr = ['apple', 'apple', 'orange', 'apple', 'banana', 'orange', 'pineapple']

会显示；

apple 3
orange 2
banana
pineapple

到目前为止，我将它们全部作为字符串返回：

arrList = myArr.join(', ');
arrList.toString()

Answer 1

漫漫长路

var elements = ["apple", "apple", "orange", "apple", "banana"];

elements.sort();

var current = null;
var count = 0;

for(var i = 0; i < elements.length; i++)
{
    if(elements[i] != current)
  {
    if(count > 0)
    {
        document.write(current + " " + count + "<br/>");
    }
    current = elements[i];
    count = 1;
  }
  else
  {
    count++;
  }
}

if(count > 0)
{
    document.write(current + " " + count);

捷径

var elements = ["apple", "apple", "orange", "apple", "banana"];

var counts = {};

elements.forEach(function(x) {
    counts[x] = (counts[x] || 0) + 1;
});

document.write("Apple: " + counts.apple + "<br/>");
document.write("Banana: " + counts.banana + "<br/>");
document.write("Orange: " + counts.orange + "<br/>");