Javascript array.filter 和 reduce答案

【问题标题】：Javascript array.filter and reduceJavascript array.filter 和 reduce
【发布时间】：2020-02-05 05:25:00
【问题描述】：

将选民对象数组转换为有多少人投票的计数请帮助我开始学习 javascript，但我对减少和过滤某些人可以修复感到很困惑？我运行代码和未定义的@@``

    function total(arr) {
    let result = arr.filter(function(votes){
   return votes !==true;
 }).reduce(function(item,cur){
   return [(+item),+(+cur)];
 },[0]);}
var voters = [
  {name:'Bob' , age: 30, voted: true},
  {name:'Jake' , age: 32, voted: true},
  {name:'Kate' , age: 25, voted: false},
  {name:'Sam' , age: 20, voted: false},
  {name:'Phil' , age: 21, voted: true},
  {name:'Ed' , age:55, voted:true},
  {name:'Tami' , age: 54, voted:true},
  {name:'Mary', age: 31, voted: false},
  {name:'Becky', age: 43, voted: false},
  {name:'Joey', age: 41, voted: true},
  {name:'Jeff', age: 30, voted: true},
  {name:'Zack', age: 19, voted: false}
];``

【问题讨论】：

voters.filter(x=>x.voted).length
谢谢大家，我就是这么做的：D

标签： javascript arrays dictionary filter reduce

【解决方案1】：

最好和最短的方法，只需过滤和计数

let voters = [
  {name:'Bob' , age: 30, voted: true},
  {name:'Jake' , age: 32, voted: true},
  {name:'Kate' , age: 25, voted: false},
  {name:'Sam' , age: 20, voted: false},
  {name:'Phil' , age: 21, voted: true},
  {name:'Ed' , age:55, voted:true},
  {name:'Tami' , age: 54, voted:true},
  {name:'Mary', age: 31, voted: false},
  {name:'Becky', age: 43, voted: false},
  {name:'Joey', age: 41, voted: true},
  {name:'Jeff', age: 30, voted: true},
  {name:'Zack', age: 19, voted: false}
];

voters.filter(person => person.voted).length

【讨论】：

【解决方案2】：

您可以使用单个 reduce 并将对象的布尔值简单地添加到计数中。

function total(array) {
    return array.reduce(function(count, voter) {
        return count + voter.voted;
    }, 0);
}

var voters = [{ name: 'Bob', age: 30, voted: true }, { name: 'Jake', age: 32, voted: true }, { name: 'Kate', age: 25, voted: false }, { name: 'Sam', age: 20, voted: false }, { name: 'Phil', age: 21, voted: true }, { name: 'Ed', age:55, voted: true }, { name: 'Tami', age: 54, voted: true }, { name: 'Mary', age: 31, voted: false }, { name: 'Becky', age: 43, voted: false }, { name: 'Joey', age: 41, voted: true }, { name: 'Jeff', age: 30, voted: true }, { name: 'Zack', age: 19, voted: false }];

console.log(total(voters));

【讨论】：