# 用reduce实现map的功能
Array.prototype.map = function (callback) {
const array = this;
return array.reduce((acc, cur, index) => {
acc.push(callback(cur, index, array))
return acc
}, [])
}
1
2
3
4
5
6
7
2
3
4
5
6
7
测试：
var m = [1,2,3,4,5].map(function (v, i, arr) {
return v + v
});
console.log(m)
1
2
3
4
2
3
4
