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