I'm trying to convert an array to an object (keyed by the first element).

foo = [1,2]

function convert_foo(foo) {
    return { foo[0]: foo[1] };
}

The following is not valid Javascript: Uncaught SyntaxError: Unexpected token [.

I've also tried:

function convert_foo(foo) {
    return ({ foo[0]: foo[1] });
}

EDIT:

It's possible this way, but I was wondering if there was a way to return it in one line.

function convert_foo(foo) {
    var obj = {}
    obj[foo[0]] = foo[1];
    return obj;
}

I'm trying to convert an array to an object (keyed by the first element).

foo = [1,2]

function convert_foo(foo) {
    return { foo[0]: foo[1] };
}

The following is not valid Javascript: Uncaught SyntaxError: Unexpected token [.

I've also tried:

function convert_foo(foo) {
    return ({ foo[0]: foo[1] });
}

EDIT:

It's possible this way, but I was wondering if there was a way to return it in one line.

function convert_foo(foo) {
    var obj = {}
    obj[foo[0]] = foo[1];
    return obj;
}

• javascript
• json

Share Improve this question Follow asked Jun 14, 2019 at 2:57 Alexander KleinhansAlexander Kleinhans 6,2781313 gold badges6666 silver badges119119 bronze badges

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2 Answers 2

Sorted by: Reset to default 4

For dynamic keys (aka puted property names in ECMAScript 2015), you have to put the key in square brackets:

function convert_foo(foo) {
    return { [foo[0]]: foo[1] };
}

console.log(convert_foo([1, 2]));

With the uping Object.fromEntries(), that is already supported on some browsers, you can also do something like this:

function convert_foo(foo)
{
    return Object.fromEntries([foo]);
}

console.log(convert_foo([1, 2]));

.as-console {background-color:black !important; color:lime;}
.as-console-wrapper {max-height:100% !important; top:0;}