babel/kneden

Unnecessary extra tick

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#47 opened on Apr 10, 2016

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 (4 comments) (3 reactions) (0 assignees)JavaScript (519 stars) (37 forks)batch import
bughelp wanted

Description

var foo = async () => {
  console.log(1);
  return (await 1) + 2;
}
foo();
console.log(2);

should transpile to:

var foo = function foo() {
  return new Promise(function (resolve) {
    console.log(1);
    resolve(1);
  }).then(function (_resp) {
    return _resp + 2;
  });
};
foo();
console.log(2);

which should log 1, then 2.

but instead transpiles to:

var foo = function foo() {
  return Promise.resolve().then(function () {
    console.log(1);
    return 1;
  }).then(function (_resp) {
    return _resp + 2;
  });
};
foo();
console.log(2);

This difference means the async function takes an extra tick - which results in logging 2, then 1.

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