({ body: { customer } } = await callCreateCustomer({
    email: createRandomEmailAddress(),
    key: 999,
    password: 'password',
}));

I don't understand what it means when you have () around the whole expression?

What does it do?

({ body: { customer } } = await callCreateCustomer({
    email: createRandomEmailAddress(),
    key: 999,
    password: 'password',
}));

I don't understand what it means when you have () around the whole expression?

What does it do?

• javascript

• 1 It's using destructuring to assign parts of the return value to the existing identifiers body and customer. – jonrsharpe Commented Aug 28, 2019 at 9:25
• 2 @jonrsharpe Might be worth pointing out, only customer gets destructed.. – Keith Commented Aug 28, 2019 at 9:34

2 Answers 2

This is Destructuring Assignment without declaration. Here customer variable is already declared above and a value is being assigned with response.body.customer

From the documentation:

The parentheses ( ... ) around the assignment statement are required when using object literal destructuring assignment without a declaration.

{a, b} = {a: 1, b: 2} is not valid stand-alone syntax, as the {a, b} on the left-hand side is considered a block and not an object literal.

However, ({a, b} = {a: 1, b: 2}) is valid, as is var {a, b} = {a: 1, b: 2}

Your ( ... ) expression needs to be preceded by a semicolon or it may be used to execute a function on the previous line.

It forces expression context so that the first { is not treated as the start of a block.