用reduce es6替换filter和map [英] replace filter and map with reduce es6

问题描述

我正在尝试避免使用过滤器和地图进行链接，但为什么我的reduce返回undefined？

I'm trying to avoid chaining with filter and map, but why my reduce returned undefined?

const data = [{
        value: "moto",
        passed: true
    },{
        value: "boat",
        passed: false
    }, {
        value: "car",
        passed: true
    }]

    // expected ['moto', 'car']
    // using filter and map
    data.filter(obj => obj.passed).map(obj => obj.value)

怎么了？
data.reduce（（accum，obj）=> obj.checked&& [... accum，obj.value]，[]）

推荐答案

 (accum, obj) => obj.checked && [...accum, obj.value]

不会返回已过滤的列表，以防对象未经检查。

does not return the filtered list, in case the object is not checked.

(accum, obj) => {
  if (obj.checked) accum.push(obj.value)
  return accum;
}

因为reducer函数会这样做。

as reducer function will do that.

或将其保留为oneliner，以保持可读性：

or to keep it as a oneliner, to not maintain readability:

(accum, obj) => obj.checked ? [...accum, obj.value] : accum;

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