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Treat "await" as an invalid identifier #4954

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merged 1 commit into from Mar 19, 2017
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Treat "await" as an invalid identifier #4954

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3 changes: 3 additions & 0 deletions ...s/babel-plugin-transform-es2015-function-name/test/fixtures/function-name/await/actual.js
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@@ -0,0 +1,3 @@
export {};

var obj = { await: function () {} };
3 changes: 3 additions & 0 deletions ...babel-plugin-transform-es2015-function-name/test/fixtures/function-name/await/expected.js
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@@ -0,0 +1,3 @@
export {};

var obj = { await: function _await() {} };
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but this changes the fn.name

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@boopathi boopathi Dec 8, 2016 •
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In chrome this happens - so defining await inside async function is syntax error. Not sure if it's a chrome bug that defining it outside is not a syntax error...

screenshot 2016-12-08 16 32 03

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The fn.name also changes when it's derived to be arguments or another keyword; not much can be done about it other than omitting the name entirely and leaving it to ES6 engines to correctly derive the name...

And yes, Chrome's error is correct. You cannot use a keyword in a var/let/const binding, and explicitly named functions create a var binding with their name.

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@Jessidhia Jessidhia Dec 8, 2016 •
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Oh, defining it outside is not a syntax error in strict mode -- it is a syntax error with the module parse goal, which only exists in Chakra(?) and parsers for now.

3 changes: 3 additions & 0 deletions packages/babel-types/src/validators.js
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Expand Up @@ -169,6 +169,9 @@ export function isReferenced(node: Object, parent: Object): boolean {
export function isValidIdentifier(name: string): boolean {
if (typeof name !== "string" || esutils.keyword.isReservedWordES6(name, true)) {
return false;
} else if (name === "await") {
// invalid in module, valid in script; better be safe (see #4952)
return false;
} else {
return esutils.keyword.isIdentifierNameES6(name);
}
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4 changes: 4 additions & 0 deletions packages/babel-types/test/validators.js
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Expand Up @@ -26,5 +26,9 @@ suite("validators", function () {

assert(t.isNodesEquivalent(parse(program), parse(program2)) === false);
});

it("rejects 'await' as an identifier", function () {
assert(t.isValidIdentifier("await") === false);
});
});
});