javascript - 简单的 JavaScript 映射——使用一个对象作为返回值

Question

我正在研究 map 函数并尝试制作一个我认为可行的人为示例。此代码工作正常:

let students = [{name: 'Susan', grades: [88, 38, 28]}, {name: 'Robert', grades: [28,97, 17]}];
let newStudents = students.map((el) => el.name);  
console.log(newStudents); // [ 'Susan', 'Robert' ]

但我真正想要的是 map 函数中的以下内容:

let newStudents = students.map((el) => {name: el.name});
// [ undefined, undefined ]
// I assumed to get back the following: [ {name: 'Susan'}, {name: 'Robert'} ]

为什么不允许在 map 函数的返回部分使用对象？

Answer 1

您需要将对象包裹在普通函数括号中。

let newStudents = students.map((el) => ({name: el.name}));
                                        ^              ^

let students = [{name: 'Susan', grades: [88, 38, 28]}, {name: 'Robert', grades: [28,97, 17]}];
let newStudents = students.map((el) => ({name: el.name}));
console.log(newStudents);