What is the Operator Precedence of Await?
In Javascript certain operators are processed before others:
1 + 2 * 3
// 1 + (2 * 3)
// 7 because * has higher precedence than +
1 === 0 + 1
// 1 === (0 + 1)
// true because + has a higher precedence than ===
The MDN has a full breakdown of all operators and their precedence ... except await
.
await getFoo() * 2; // await (getFoo() * 2) or (await getFoo()) * 2?
await getFoo() === 5; // await (getFoo() === 5) or (await getFoo()) === 5?
Can anyone explain which operators are processed before/after await?
Right now I feel like I have to add a bunch of parenthesis that are probably unnecessary because I'm not sure what will get handled before/after await
. And while I know I should just be able to look this up, even MDN (the gold standard of documentation IMHO) doesn't have the answer.
Solution 1:
An AwaitExpression is a UnaryExpression and has the same precedence as delete
, void
, typeof
, +
, -
, ~
, and !
, binding stronger than any binary operator.
This is unlike yield
which has a precedence lower than anything else except the comma operator. This design decision was made because both yield a+b
and await a + await b
are scenarios thought to be more common than (yield a) + (yield b)
and await (a + b)
.