通过特定属性过滤和排列[关闭]
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您好，我有以下对象的javascript数组：
runners = [
{ id: 1, first_name: "Charmain", last_name: "Seiler", email: "cseiler0@wired.com", shirt_size: "2XL", company_name: "Divanoodle", donation: 75 },
{ id: 2, first_name: "Whitaker", last_name: "Ierland", email: "wierland1@angelfire.com", shirt_size: "2XL", company_name: "Wordtune", donation: 148 },
{ id: 3, first_name: "Julieta", last_name: "McCloid", email: "jmccloid2@yahoo.com", shirt_size: "S", company_name: "Riffpedia", donation: 171 },
{ id: 4, first_name: "Martynne", last_name: "Paye", email: "mpaye3@sciencedaily.com", shirt_size: "XL", company_name: "Wordware", donation: 288 },
{ id: 5, first_name: "Gussy", last_name: "Raraty", email: "graraty4@ucoz.ru", shirt_size: "L", company_name: "Oozz", donation: 291 },
];
我正在尝试解决以下挑战，我真的不知道我在做什么错。如果有人可以帮助，这是我设法写的，我知道这是不正确的，但我不知道为什么。
/**
* ### Challenge `getRunnersByTShirtSize`
*
* @instructions
* The event director needs a way to find the runners that need
* a specific t-shirt size, so they can place the orders easily.
* Implement this function using filter().
*
* @param runners array of runners like the one inside the /data/runners.js file.
* @param tShirtSize string (possible values are "S", "M", "L", "XL", "2XL", "3XL").
* @returns an array containing only the runners that use the given `tShirtSize`.
* The runners in the array appear in the same order they appear in the `runners` array.
*/
function getRunnersByTShirtSize(runners, tShirtSize) {
/* CODE HERE */
const newSize = runners.filter((size) => {
return runners.size == tShirtSize;
});
return newSize;
}
答案
应该是runner.shirt_size而不是runners.size并且您应该引用在函数filter((runner)
function getRunnersByTShirtSize(runners, tShirtSize) {
/* CODE HERE */
const newSize = runners.filter((runner) => {
return runner.shirt_size == tShirtSize; //<===== not runners.size but instead shirt_size
});
return newSize;
}
您还可以像这样摆脱多余的变量：
function getRunnersByTShirtSize(runners, tShirtSize) {
return runners.filter(runners=> runners.shirt_size == tShirtSize);
}
另一答案
filter方法接受一个回调，它是一个将数组元素作为第一个参数的函数。它使您可以遍历数组并过滤掉不需要的元素。这样做，回调函数必须返回一个布尔值：true将元素保留在返回的数组中，false将其保留。
这里您正在将数组每个元素的属性shirt_size与函数的第二个参数进行比较。因此，回调必须返回属性shirt_size等于tShirtSize。
function getRunnersByTShirtSize(runners, tShirtSize) { return runners.filter((runner) => { return runner.shirt_size == tShirtSize; }); } console.log(getRunnersByTShirtSize(runners, '2XL'))<script>const runners=[{id:1,first_name:"Charmain",last_name:"Seiler",email:"cseiler0@wired.com",shirt_size:"2XL",company_name:"Divanoodle",donation:75},{id:2,first_name:"Whitaker",last_name:"Ierland",email:"wierland1@angelfire.com",shirt_size:"2XL",company_name:"Wordtune",donation:148},{id:3,first_name:"Julieta",last_name:"McCloid",email:"jmccloid2@yahoo.com",shirt_size:"S",company_name:"Riffpedia",donation:171},{id:4,first_name:"Martynne",last_name:"Paye",email:"mpaye3@sciencedaily.com",shirt_size:"XL",company_name:"Wordware",donation:288},{id:5,first_name:"Gussy",last_name:"Raraty",email:"graraty4@ucoz.ru",shirt_size:"L",company_name:"Oozz",donation:291}];</script>
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