Move "use strict" directives to the first line of each file. In
particular, move them above any ESLint comments, which are far less
important.
There are few exceptions:
Executable files
In these, the "use strict" directive must give way to the shebang.
lib/parser.js
Here, the "Generated by..." comment comes first. Also, ESLint
comments are prepended in post-processing.
Use one var/let/const per variable, but only for initialized variables.
Uninitialized variables are still grouped into one var/let/const
declaration as I don't see any value in separating them. This approach
reflects the fact that initialized and uninitialized var/let/const
declarations are really two different things.
See #443.
The for-in statement in JavaScript iterates also over inherited
properties. This is typically not desired and requires adding a
check using Object.prototype.hasOwnProperty inside the loop.
This commit replaces all for-in statements and related checks inside
them with iteration over Object.keys(...). The iteration is performed
using either Array.prototype.forEach of a plain for loop.
Because arrow functions work rather differently than normal functions (a
bad design mistake if you ask me), I decided to be conservative with the
conversion.
I converted:
* event handlers
* callbacks
* arguments to Array.prototype.map & co.
* small standalone lambda functions
I didn't convert:
* functions assigned to object literal properties (the new shorthand
syntax would be better here)
* functions passed to "describe", "it", etc. in specs (because Jasmine
relies on dynamic "this")
See #442.
This is purely a mechanical change, not taking advantage of block scope
of "let" and "const". Minimizing variable scope will come in the next
commit.
In general, "var" is converted into "let" and "const" is used only for
immutable variables of permanent character (generally spelled in
ALL_CAPS). Using it for any immutable variable regardless on its
permanence would feel confusing.
Any code which is not transpiled and needs to run in ES6 environment
(examples, code in grammars embedded in specs, ...) is kept unchanged.
This is also true for code generated by PEG.js.
See #442.
This will allow to use ES2015 constructs in benchmark code.
The change required introducing a small server, which serves both PEG.js
and benchmark code passed through Babel and bundled together. This
allowed to convert the benchmark to regular modules and to get rid of
the hackery that was previously needed to make it run both in Node.js
and in the browser.
Note the benchmark no longer exercises the browser version.
See #442.
This will allow to use ES2015 constructs in spec code.
The change required introducing a small server, which serves both PEG.js
and spec code passed through Babel and bundled together. This allowed to
convert the specs to regular modules and get rid of the hackery that was
previously needed to make them run both in Node.js and in the browser.
Note the specs no longer exercise the browser version. This will allow
to spec PEG.js internals in the future.
See #442.
David Majda
Mingun