javascript - 在整个变量表达式周围有 () 的这个 javascript 语法是什么？

Question

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

我不明白当你在整个表达式周围使用 () 是什么意思？

它有什么作用？

Answer 1

这是没有声明的解构赋值。这里 customer 变量已经在上面声明，并且正在使用 response.body.customer

分配一个值

来自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.