Reduce in the array

Source: Internet
Author: User

The first time the reduce method feels like a chicken to me, but in-depth understanding, it is a very powerful and practical way to discover the mystery.

var arr = [1,2,3,4,5,6,7]; var sum = Arr.reduce ((res,now) ={//Parameter res represents the returned result, now represents the current item, and the first traversal by default res is the first item in the        array,  Return res + now ;    }); Console.log (sum);        //  -

The above is a very practical example, the accumulation of each item in the data,

var arr = [1,2,3,4,5,6,7]; var sum = Arr.reduce ((res,now) =>{ // parameter res represents the returned result, now represents the current item, and the first traversal by default, RES is the first item in the array.              return res + now ;    },10); Here the 10 identifies the initial value of res, writable, non-writable, default is the first item in the array console.log (sum);        //  -

Reduce in the array

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