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140

ECMAScript 6 arrow function that returns an object

rated 0 times [ 145] [ 5] / answers: 1 / hits: 149436 / 9 Years ago, fri, february 27, 2015, 12:00:00

When returning an object from an arrow function, it seems that it is necessary to use an extra set of {} and a return keyword because of an ambiguity in the grammar.

That means I can’t write p => {foo: bar}, but have to write p => { return {foo: bar}; }.

If the arrow function returns anything other than an object, the {} and return are unnecessary, e.g.: p => foo.

p => {foo: bar} returns undefined.

A modified p => {foo: bar} throws “SyntaxError: unexpected token: ':'”.

Is there something obvious I am missing?

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answered 9 Years ago mariann · Accepted Answer

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

p => ({ foo: 'bar' });

You don't need to wrap any other expression into parentheses:

p => 10;

p => 'foo';

p => true;

p => [1,2,3];

p => null;

p => /^foo$/;

and so on.

Reference: MDN - Returning object literals