Array.prototype.reduceRight() methods only differ in terms of how they traverse elements of an array:
Array.prototype.reduce()starts from left-to-right;
Array.prototype.reduceRight()starts from right-to-left.
Other than that, there are no differences between the two; they both apply the given function against an accumulator and each value of the array, to reduce it to a single value.
Consider the following example, which illustrates the difference between the two:
const arr = ['a', 'b', 'c', 'd']; const ltr = arr.reduce((previous, current) => previous + current); const rtl = arr.reduceRight((previous, current) => previous + current); console.log(ltr); // 'abcd' console.log(rtl); // 'dcba'
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