unexpected token : using map to form array of object

Question

I want to produce this

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

My below code failed, got expected token?

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)

prasanth · Accepted Answer · 2017-06-05T11:03:22.323

14

you are missing the () change like this ({name:obj.name, age:obj.age})

You must wrap the returning object literal into parentheses. Otherwise curly braces will be considered to denote the function’s body. Next works:

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)

edited Jun 05 '17 at 11:03

answered Jun 05 '17 at 11:00

prasanth

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would `new Object({name:obj.name, age:obj.age})` work too? – Ayoub Laazazi Jun 20 '20 at 15:49
@AyoubLaazazi .. Ya of course. But `({})` is enough .short form declaration. – prasanth Jun 21 '20 at 09:06

score 2 · Answer 2 · answered Jun 05 '17 at 11:00

2

When creating objects with arrow expressions, you'll need to wrap the body in parens, or it'll be parsed as an arrow function:

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

answered Jun 05 '17 at 11:00

AKX

152,115
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score 1 · Answer 3 · answered Jun 05 '17 at 11:07

Just as a reference, this would also work, and be the same:

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);

unexpected token : using map to form array of object

3 Answers3

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