As patched in #1597, `make_node_from_constant()` makes inconsistent and sometimes incorrect calls to `optimize()` and `transform()`.
Fix those issues properly by changing the semantics of `evaluate()` and `make_node_from_constant()`, with the side effect that `evaluate()` no longer eagerly converts constant to `AST_Node`.
Liberal use of `Compressor.transform()` and `AST_Node.optimize()` presents an issue for look-up operations like `TreeWalker.in_boolean_context()` and `TreeWalker.parent()`.
This is an incremental fix such that `AST_Node.optimize()` would now contain the correct stack information when called correctly.
Self-referenced function has non-fixed values assigned to its parameters.
Let `unused` & `!keep_fnames` do the scanning, then apply `reduce_vars` only to unnamed functions.
fixes#1595
- one-use function call => IIFE should take `eval()` & `arguments` into account
- if unused parameter cannot be eliminated, replace it with `0`
fixes#1583
those were not optimised for `unused` before, which made it necessary for `reduce_vars` to have separate steps for `keep_fnames`
docs update by @kzc
closes#1577
Function expression can be assigned to a variable and be given a name. Ensure function name is the reduced variable before clearing it out.
fixes#1573fixes#1575
`unsafe` turns undefined keyword into a variable of the same name if found, but that interferes with other related optimisations.
Keep track of such transformations to ensure zero information loss in the process.
Bookmarklet for instance implicitedly assumes a "completion value" without using `return`.
The `expression` option now supports such use cases.
Optimisations on IIFEs also enhanced.
fixes#354fixes#543fixes#625fixes#628fixes#640closes#1293
Avoid variable substitution in the following cases:
- use of variable before declaration
- declaration within conditional code blocks
- declaration within loop body
fixes#1518fixes#1525
Patched up `make_node()` without `orig`.
There may be other cases where `start` could be missing, so make it print "undefined" instead of crashing.
fixes#1518
Modules like webpack and grunt-contrib-uglify still uses `ast.transform(compressor)` before `Compressor.compress(ast)` was introduced.
Workaround this compatibility issue by deactivating `reduce_vars` in such case.
Also fix use case with omitted `options` when calling `Compressor()`.
fixes#1516
- Use AST_Destructuring for lhf assignment patterns
- Use AST_DefaultAssign for default assignments
- Add more checks for lhs expressions
- Add lots of testing
- Cleanup ast (e.g. remove default property)
- Fix#1402 based on a patch from @kzc
- Refine spread allowance in array destructring pattern
- Add destructuring AST tree checker
A function call or IIFE with an immediately preceding comment
containing `@__PURE__` or `#__PURE__` is deemed to be a
side-effect-free pure function call and can potentially be
dropped.
Depends on `side_effects` option.
`[#@]__PURE__` hint will be removed from comment when pure
call is dropped.
fixes#1261closes#1448
- support arrays, objects & AST_Node
- support `"a.b":1` on both cli & API
- emit warning if variable is modified
- override top-level variables
fixes#1416closes#1198closes#1469
- remove extra tree scanning phase for `negate_iife`
- `negate_iife` now only deals with the narrowest form, i.e. IIFE sitting directly under `AST_SimpleStatement`
- `booleans`, `conditionals` etc. will now take care the rest via more accurate accounting
- `a(); void b();` => `a(); b();`
fixes#1288closes#1451
- assign statement does not count towards variable usage by default
- only works with assignments on the same scope level as declaration
- can be disabled with `unused` set to "keep_assign"
- `toplevel` to drop unused top-level variables and/or functions
- `top_retain` to whitelist top-level exceptions
closes#1450
- remove call to evaluate() in is_constant() and let nested optimize() does its job instead
- reject RegExp in is_constant() and remove special case logic under collapse_vars
- operands to conditionals optimisation are now always evaluate()-ed
- throw error in constant_value() instead of returning undefined to catch possible bugs, similar to make_node_from_constant()
- optimise binary boolean operators under `evaluate` instead of `conditionals`
* Fixes#1147: template strings not obeying -b ascii_only true
* Allow evaluation of template expressions by adding optimizers and
walkers
* Make sure tagged templates are never changed
* Remove template tokenizer in parser, add template tokenizer in
tokenizer. It is using a brace counter to track brace position of
templates
* Add tokens `template_head` and `template_substitution` but parsing
tokens stays mostly the same
* Do not output strings anymore in AST_TemplateString, instead use
AST_TemplateSegment
* Fix parsing tagged templates, allowing multiple templates behind
as spec allows this
These changes don't influence tagged templates because raw content
may influence code execution, however they are safe to do in normal
templates:
* Allow basic string concatenation of templates where possible
* Allow custom character escape style similar to strings, except in
tagged templates
Note that expressions are still compressed in tagged templates.
Optional things that may be improved later:
* Custom quote style for templates if it doesn't have expressions.
Making it obey the quote_style option if this is the case.
Has little or no impact on minification size in the majority of
cases but can speed up rollup builds significantly.
This sequences change also has the beneficial side effect of avoiding
"stack size exceeded" errors on very large input files.
The user is free to alter the sequences limit if they are so inclined.
The previous sequences limit was 2000. 20 is often sufficient.
catch identifier is mangled correctly for ES5 standards-compliant JS engines by default.
Unconditionally use the ie8 if/do-while workaround whether or not --screw-ie8 is enabled.
To support non-standard ie8 javascript use: uglifyjs --support-ie8
- Partially reverting 91cdb93e57 and eaf3911c31 and reimplement
- Add generators support for objects and classes
- Only classes can have static methods so restrict use of it
Special thanks to @rvanvelzen and @kzc for reviewing this patch and
providing constructive feedback over and over again.
- Make let, const, and class symbols be declared in a block scope.
- Piggy back on existing catch symbol implementation to get block-aware mangling working
- Make sure unused block-scoped declarations can be dropped
- Don't eliminate a block if it has a block-scoped declaration
- Remove silly empty anonymous blocks left over from drop_unused
- AST_Toplevel now gets to call drop_unused too, since block-scoped variables aren't global!
- Don't consider block declarations global
It's now available during tree walking, i.e. walker.has_directive("use
asm"), rather than as part of the scope. It's thus no longer necessary
to call `figure_out_scope` before codegen. Added special bits in the
code generator to overcome the fact that it doesn't inherit from
TreeWalker.
Fix#861
