Keeping the shape of an object constant is a performance improvement for modern javascript engines. At the point of the code change it is certain that the `children` property will be set later, so the property can already be set to `undefined`.
* First implementation sketch and testcase
* Use helper instead of inline IIFE's
* minNodeVersion 6.0.0
* Hoisted visitor for subtraversal and fixed edgest case
* Resolve merge conflicts in helpers
* Remove duplicated helper from messing up Git
* for-of: IteratorClose spec compatibility.
See #3:
https://tc39.github.io/ecma262/#sec-iteratorclose
* Update spec fixtures for for-of.
* Fix IteratorClose case for remap-async-to-generator.
* Fix IteratorClose case for async-generator-function test output.
* Modify few tests according to iteratorClose fix.
* Fix iteratorClose for helpers.slicedToArray also.
* Update iteratorClose fixture for commonjs.
The for-in loop in helpers.defineEnumerableProperties doesn't iterate over Symbols.
If Object.getOwnPropertySymbols exists, include the discovered values when defining properties.
* Create "babel-helper-wrap-function"
It contains the logic to wrap a function inside a call expression.
It was part of the "babel-helper-remap-async-to-generator" package, but
it is needed to transpile "function.sent"
* Create "babel-transform-function-sent"
It transforms the "function.sent" meta property by replacing it with
"yield" and making the generator ignore the first ".next()" call.
* "function.sent" is the last value passed to .next(), not the first one
* Disable exec tests on old node
* Fix flow error
* Add "transform-function-sent" to "stage-2" preset
* Do every trasformation in one traversal
* Test for "yield function.sent"
* [skip ci]
* Fix some typos [skip ci]
* moved applying arguments inside new Promise handler block
* updated test fixture to reflect change
* corrected the apply to use correct scope and arguments
* added regression test for issue #4943, added async-to-generator/async-default-arguments test
* added regression test for issue #4943
* switched back to using arrow function, since now pointing to v7 release base branch
* simplified async-to-generator regression test for issue #4943, imrproved change to self/arguments refs by using arrow function on returned promise
* updated text fixtures
* removed es2015 preset usage from issue #4943 regression exec test
* added use strict to test fixture
* added use strict to test fixture
* added destructing transform to test options
* removed use strict from exec test
* added parameters & destructing transforms to test
* Removed unnecessary 'return' statements.
Returning a 'Promise' value in 'promise.then()' makes promise chains.
Used memory and promises are not garbage collected
until finishing 'helpers.asyncToGenerator'.
* Update test
* formatting
* fix `typeof Symbol.prototype`
Babel uses a helper function to return the correct value for `typeof
obj` when obj is a Symbol and support for Symbol has been polyfilled.
This function assumes that `obj.constructor === Symbol` implies `typeof
obj === 'symbol'`.
This isn't true when obj is `Symbol.prototype`. In that case (REPL from
node 6, the same holds in Firefox):
```
> Symbol.prototype.constructor === Symbol
true
> typeof Symbol.prototype
'object'
>
```
AFAICS, that's the only case where the assumption doesn't hold.
The test added by this patch fails only on node 0.10, as 0.12 already
has a native implementation of Symbol and the polyfill code doesn't run.
This caused a problem in core-js when it's compiled with babel (the
issue was isolated by @skozin here:
https://github.com/zloirock/core-js/issues/189#issuecomment-209864582).
- Have the `jsx` helper do the `defaultProps` work instead of calling `defaultProps` inline.
- Put `key` after `props` and make it optional.
- Inline `children` as rest args instead of in the object.
- Rename `createRawReactElement` to `jsx`. I wish I was kidding.
Most of these are silly microoptimizations. In my test file (based off an internal RN app), this reduces the parsing overhead of inlining from around 1% to 0.1% in JSC and from 0.6% to 0.0% in V8 (compared to element inlining before this commit).
Once parsed, the initial render with inlining is the same speed as not inlining in JSC and ~1% slower in V8. A second initial render in the same context (reusing the function objects, JIT, etc) is 2.0% faster in JSC and 5.5% faster in V8.
Either due to lower parsing costs or better type inference, this seems
to perform better than direct object inlining. (All along, the main win
was skipping a loop through props, not avoiding a function call.)
