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Flip default parameter template (#4515)

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* Flip default parameter template

YMMV, I saved ~10b on a 2kb library. Not noticeable at the small scale, by why not do it anyway?

I've (unscientifically) found that flipping the default parameter conditional yields better gzip results. I think this is due to the slightly longer string it can now repeatedly match:

```js
// old
var param = arguments.length <= 0 || void 0 === arguments[0] ? null : arguments[0]
--------------------------------------------------------------^

// new
var param = arguments.length > 1 && void 0 !== arguments[1] ? arguments[1] : null
------------------------------------------------------------------------^
```

Though it's entirely likely gzip will also choose up to the index of the arguments if you many default parameters at different indexes.

* Update tests
This commit is contained in:
Justin Ridgewell
2016-09-25 17:05:53 -04:00
committed by Logan Smyth
parent 08b45ca853
commit c2ed9de7fb
10 changed files with 31 additions and 31 deletions
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6
packages/babel-plugin-transform-es2015-parameters/src/default.js
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@@ -7,10 +7,10 @@ import * as t from "babel-types";
let buildDefaultParam = template(`
let VARIABLE_NAME =
ARGUMENTS.length <= ARGUMENT_KEY || ARGUMENTS[ARGUMENT_KEY] === undefined ?
DEFAULT_VALUE
ARGUMENTS.length > ARGUMENT_KEY && ARGUMENTS[ARGUMENT_KEY] !== undefined ?
ARGUMENTS[ARGUMENT_KEY]
:
ARGUMENTS[ARGUMENT_KEY];
DEFAULT_VALUE;
`);
let buildCutOff = template(`