[英]How do I count the number of occurrences of a value in an array without mutation
[英]How do i multiply numbers in Type Script in a array like [{ count: 3, value: 2 },{ count: 7, value: 1 }] such that the answer is 3*2 + 7*1 = 13?
假設我有這個數組:
[{ count: 3, value: 2 },{ count: 7, value: 1 }]
如何將數字相乘使答案為 13?
我想編碼來做:
3*2 + 7*1 = 13
您可以使用Array.prototype.reduce來執行此操作:
const arr = [{ count: 3, value: 2 },{ count: 7, value: 1 }]; const val = arr.reduce((acc, item) => acc + (item.count * item.value), 0); console.log(val);
您還可以使用以下代碼對所有鍵(例如,不僅是計數和值)執行此操作:
const arr = [{ count: 3, value: 2 },{ count: 7, value: 1 }]; const val = arr.reduce((acc, item) => acc + Object.values(item).reduce((a,b) => a * b, 1), 0); console.log(val);
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