组数组并计数 [英] group array and get count

问题描述

说我有这样的数组:

[
   "foo",
   "bar",
   "foo"
   "bar",
   "bar",
   "bar",
   "zoom"
]

我想对它进行分组，这样我就可以得到一个计数:

I want to group it so I can get a count like so:

{
  "foo": 2,
  "bar": 4,
  "zoom": 1
}

有可以执行此操作的实用程序吗?

is there a utility that can do this?

推荐答案

只需使用函数Array.prototype.reduce.

let array = [   "foo",   "bar",   "foo",   "bar",   "bar",   "bar",   "zoom"],
    result = array.reduce((a, c) => (a[c] = (a[c] || 0) + 1, a), Object.create(null));

console.log(result);

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

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