從數組中過濾數據並將其分組在javascript 中？

Question

我有一個如下所示的數組

OStatus=["hold","approved","rejected","hold","approved","rejected","hold","approved"]

我想要這樣的結果

Oinfo=["hold":3,"approved":3,"rejected":2].

Answer 1

假設您想生成一個對象，該對象將作為輸入數組元素的鍵映射到作為每個元素計數的值，您可以使用 Array.reduce，如下所示：

Oinfo = OStatus.reduce((acc, x) => ({ ...acc, [x]: (acc[x] || 0) + 1 }), {})