Question

我想制作这个

[
        {name: "james", age: 10},
        {name: "john", age: 12},
        {name: "johnny", age: 56}
    ]

我的下面的代码失败了，得到了预期的令牌？

let x = [
    {name: "james", age: 10, school: "London"},
    {name: "john", age: 12, school: "India"},
    {name: "johnny", age: 56, school: "USA"}
]

let y = x.map(obj => {name:obj.name, age:obj.age})

console.log(y)

Answer 1

您错过了此()

之类的({name:obj.name, age:obj.age})更改

您必须将返回的对象文字包装到括号中。除此以外花括号将被视为表示函数的主体。下一个工作原理：

Reference question

let x = [
    {name: "james", age: 10, school: "London"},
    {name: "john", age: 12, school: "India"},
    {name: "johnny", age: 56, school: "USA"}
]

let y = x.map(obj => ({name:obj.name, age:obj.age}))

console.log(y)

Answer 2

使用箭头表达式创建对象时，您需要将主体包裹在parens中，或者将其解析为箭头函数：

let y = x.map(obj => ({name: obj.name, age: obj.age}));

Answer 3

作为参考，这也可以，并且是相同的：

let x = [
    {name: "james", age: 10, school: "London"},
    {name: "john", age: 12, school: "India"},
    {name: "johnny", age: 56, school: "USA"}
];

let y = x.map(obj => {
  return { name:obj.name, age:obj.age };
});

console.log(y);

意外令牌：使用map形成对象数组

3 个答案: