Question

我有一个如下所示的JavaScript数组

var userMale = [];
var userData = [
                {userId: "100", userName: "John", gender: "M"},
                {userId: "101", userName: "Emma", gender: "F"},
                {userId: "102", userName: "Alex", gender: "F"},
                {userId: "103", userName: "Sam", gender: "M"}
              ]

我需要根据性别状况将所有userId放入不同的数组中，即所有男性都应位于userMale数组中

我已经编写了以下代码来实现这一目标。它有效，但是，我希望避免for和if循环

for(var i=0; i<userData.length; i++) {
    if(userData[i].gender == "M") {
        userMale.push(userData[i].userId);
    }
}

console.log("userMale: ", userMale);

Answer 1

您可以使用filter。

var userData = [
                {userId: "100", userName: "John", gender: "M"},
                {userId: "101", userName: "Emma", gender: "F"},
                {userId: "102", userName: "Alex", gender: "F"},
                {userId: "103", userName: "Sam", gender: "M"}
              ]
              
let userMale = userData.filter(data => {
  return data.gender === "M"
})

console.log(userMale)

Answer 2

您需要使用filter函数

var userData = [
                    {userId: "100", userName: "John", gender: "M"},
                    {userId: "101", userName: "Emma", gender: "F"},
                    {userId: "102", userName: "Alex", gender: "F"},
                    {userId: "103", userName: "Sam", gender: "M"}
                  ]

    let userMale = userData.filter(data => {
      return data.gender === "M"
    })

    let userFemale = userData.filter(data => {
      return data.gender === "F"
    })

Answer 3

您可以使用Underscore.js中的def year_info(year, yearly_weather): try: k = year v = yearly_weather[k] return "{:<8.0f}| {:<18.2f}| {:>12.2f} | {:>10.2f} | {:>10.0f}| {:>10.0f}" .format(k, *v) except KeyError: return "{:^8s}| {:^18s}| {:^12s} | {:^10s} | {:^10s} | {:^10s}".format(*['N/A']*6)

res = year_info(1965, yearly_weather) '1965 | 43.00 | 33.00 | 0.27 | 1| 1'返回列表中的值，但不包含真值测试（谓词）通过的元素。

reject

Answer 4

由于您希望同时将元素过滤并投影到userId上，因此使用Array.reduce的方法似乎是最合适的方法。看到这里：

var userData = [
                {userId: "100", userName: "John", gender: "M"},
                {userId: "101", userName: "Emma", gender: "F"},
                {userId: "102", userName: "Alex", gender: "F"},
                {userId: "103", userName: "Sam", gender: "M"}
              ];
              
const convert = (data) => data.reduce((result, { userId, gender }) => {
  if (gender === 'M') {
    return result.concat(userId);
  } 
  
  return result;
}, []);   

var userMale = convert(userData);

console.log(userMale);

Answer 5

使用原始JavaScript：

var userData = [
  {userId: "100", userName: "John", gender: "M"},
  {userId: "101", userName: "Emma", gender: "F"},
  {userId: "102", userName: "Alex", gender: "F"},
  {userId: "103", userName: "Sam", gender: "M"}
];

function getMaleFemale ()
{
  // Create an array for each gender
  let male = [], female = [];
  
  // For each user, check if gender is F, if so, push id to female else to male
  userData.forEach( user => ( user.gender === 'F' ? female : male ).push( user.userId ) );
  
  // Return male and female
  return { male, female };
}

// Usage example
let { male, female } = getMaleFemale();

// Do something with male and female

console.log( 'male :', male );
console.log( 'female :', female );

Answer 6

FK82's approach的简洁版本。

let userMale = userData.reduce((result, user) =>
    user.gender === 'M' ? result.concat(user.userId) : result
, [])

根据条件从数组获取值集

6 个答案: