如何保存對Array方法的引用？

Question

有沒有辦法實現這種行為？

提前致謝。

const filterBy = (arr, side) => {
    const reduceFunc = side === 'left' ? reduce : reduceRight;

    arr.reduceFunc(...)
}

Answer 1

是的，您只需要獲取一個字符串，然后使用括號符號即可訪問Array.prototype上的相應函數：

 const filterBy = (arr, side) => { const propName = side === 'left' ? 'reduce' : 'reduceRight'; // silly minimal example, will simply return the last item that's iterated over: return arr[propName]((a, item) => item); } const arr = [1, 2]; // Reduces starting from left, last item iterated over will be 2: console.log(filterBy(arr, 'left')); // Reduces starting from right, last item iterated over will be 1: console.log(filterBy(arr, 'right'));