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This article mainly shows you "how to use the reduce () and reduceRight () methods in JavaScript". The content is simple and clear. I hope it can help you solve your doubts. Let the editor lead you to study and learn how to use the reduce () and reduceRight () methods in JavaScript.

Reduce () and reduceRight ()

Reduce () execution order is from left to right reduceRight () execution order is from right to left

The callback function is executed for each element of the array in turn, which is generally used for accumulators.

There are four parameters, the first of which is the initial value or the return value at the end of the calculation. The second is the current element. The third is the index of the current element. The fourth is the array object to which the current element belongs.

Initiavalue: when the array is empty, you can set the initial value passed to the function and put it after the object

Var str1 = [1arr.reduce (function (total,num,index,add) {return total+num})] / / the use of the accumulator console.log (str1.reduce (total,num,index,add) {return total+num}); / / the use of var arr= [] console.log (function (total) {return total}, 0)); / / above is all the contents of this article entitled "how to use reduce () and reduceRight () methods in JavaScript". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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