• JS: put variable declarations after "use strict", fixes #343
• JS: don't convert hexadecimal representations in strings from 0x80 upwards unless it's UTF-8, fixes #341
• JS: don't merge var declarations after for statement into for initializer, fixes #346
• JS: add parenthesis when necessary to if condition when converting to conditional expression, fixes #347

• Improve error contexts when the file contains unicode characters
• HTML: revert change in v2.9.5 that removed spaces between attributes, fixes #342
• JS: fix bug that converted (function(){})() to !function(){}() which modifies the return value, fixes #340

• cmd: add JS options
• JS: remove unassigned bindings in for statement initializer when it cannot be merged with variable declaration
• JS: use Precision option in minifying numbers
• SVG: fix bugs in skipping foreignObject tags

• JS: add var decl as undeclared in block scopes between the current scope and the function scope, fixes #334
• JS: fix overwriting next statement in if-else => if-if conversion, fixes #335

• cmd: minify input even if extension is unknown but type/mimetype is given
• CSS: fix timeout in property with many commas
• CSS: convert RGBA to transparent only if the color is fully transparent black (and not any other transparent color), fixes #332
• CSS: fix crash when rgb/rgba functions have less than three arguments
• CSS: fix box-shadow value none conversion to 0 0 as they are not equivalent, fixes #332
• HTML: remove space between attributes when after a quoted value
• HTML: keep empty title and lang attributes, fixes #331
• JS: merge variable declarations even if one has an ObjectPattern
• JS: remove trailing commas in BindingArray (except when Rest ellipsis is set)
• JS: add parenthesis around object literal in arrow function body, fixes #333

• JS: don't remove braces when there are lexical declarations, fixes #326
• JS: don't convert lexical declarations to expressions when hoisting variables, fixes #326
• JS: merge variable declaration and for initializer with variable declaration

• JS: only put var declaration into for or while, and not let nor const, fixes #325
• JS: merge more efficiently a var declaration with a for or while statement

• Add JS (ECMAScript 2020) minifier
• Improve benchmark functions
• Predefine byte-slices instead of inline for performance
• Don't check write errors to output during minification, but check at the end only
• Lexers/parser now require passing parse.Input instead of io.Reader
• Rename subpackage min to minify

JS minifier overview

Features:

• remove superfluous whitespace
• remove superfluous semicolons
• shorten true, false, and undefined to !0, !1 and void 0
• rename variables and functions to shorter names (not in global scope)
• move var declarations to the top of the global/function scope (if more than one)
• collapse if/else statements to expressions
• minify conditional expressions to simpler ones
• merge sequential expression statements to one, including into return and throw
• remove superfluous grouping in expressions
• shorten or remove string escapes
• convert object key or index expression from string to identifier or decimal
• merge concatenated strings
• rewrite numbers (binary, octal, decimal, hexadecimal) to shorter representations

It compresses files at about 25 MB/s (only minifying, not considering reading/writing files) which is (much) faster than existing minifiers. Compression rate is between 1.5 and 3.0 depending on the file (respectively, the compression file size is between 35% -- 65% of the original). Example of known files:

The minifier has been tested for a number of web applications including WordPress. The go-fuzz fuzzer has been used extensively in order to detect bugs, and will continue finding bugs using https://github.com/google/oss-fuzz

WARNING for package maintainers, some files have been renamed, adjust your build scripts accordingly.

• Use Makefile instead of GoReleaser to build releases for all architectures, use make release. This fixes the README.md file location inside the archives to be in the root of the archive
• Release archives will no longer have the version name explicitly stated, fixes #316
• Remove cmd/minify/install.sh, use make install instead
• Rename cmd/minify/minify_bash_tab_completion to cmd/minify/bash_completion
• Rename LICENSE.md to LICENSE as it is not a Markdown file
• Rename min subpackage to minify
• cmd: running minify without arguments will print a more informative error message
• cmd: bad arguments will not display cmd usage automatically

• cmd: fix file paths on Windows when input and output directories are equal (slash vs backslash)
• cmd: add --cpuprofile and --memprofile options
• cmd: fix usage of --match and --sync simultaneously, fixes #315
• cmd: --match applies to all filename inputs not just under directories
• CSS: remove whitespace around custom variable value, fixes #305
• JSON: minify numbers, fixes #302
• HTML: fix slow parsing of <a> tag with many name or id attributes (OSS-Fuzz)
• Don't replace space by + in DataURI, fixes #314
• Don't escape @ : ; = ? + , / $ \t \n \r in DataURIs (works for Chrome, Firefox, Opera, Edge, Safari, Yandex, and IE9, IE10, IE11)

• HTML: remove text and whitespace within select and optgroup tags
• CSS: fix slow parsing of selectors when they contain many errors
• CSS: fix RGB/HSL when a parameter overflows
• CSS: fix slow parsing of large HSL parameters
• cmd: properly run defer calls after command ends, may fix some race bugs
• Add easy API in the min/ subpackage
• Add project to OSS-Fuzz

• CSS: fix minification of flex, default of flex-basis is zero for three value case, fixes #292
• CSS: remove whitespace within @import url(...), fixes #296
• HTML: remove spaces around/in picture and audio following whitespace removal rules for phrasing elements

• external minifiers can now use input/output files instead of only stdin/stdout using the $in and $out keywords
• SVG: don't minify inside foreignObject, fixes #291

• SVG: bugfix for C, S, Q, and T commands where if the control points would not overlap with the start or end points of the curve, it would still be converted to a line.

• Use custom URL encode/decode functions to fix #180 and #243
• Decimal and Number now take precision to mean the number of significant digits, and not the number of digits behind the dot (decimals); includes a few subtle bugfixes. Decimals option renamed to Precision
• Move Hash definitions and EntitiesMap from tdewolff/parse to this repository to prevent releasing new versions of tdewolff/parse everytime
• cmd: add --sync functionality
• cmd: make --watch work for newly created directories
• cmd: various fixes and improved messages
• CSS: keep quotes around IE font families, fixes #251
• CSS: major refactor to allow nested functions to be minified
• CSS: improved HSL/RGB minification
• CSS: minify more properties: color, background-color, border-color, border-*-color, caret-color, outline-color, fill, stroke, column-rule, text-shadow, text-decoration, text-emphasis, flex, flex-*, order, fixes #217
• CSS: minify background better if it has multiple layers
• CSS: improve box-shadow minification
• CSS: accept CSS functions where numbers/lengths are required, such as calc, min, max, clamp, attr, var
• SVG: print new path command after bad command, fixes #275
• SVG: print A command correctly with boolean largeArc and sweep
• SVG: avoid precision errors for alternative (absolute or relative commands) path

Upgrade to tdewolff/parse@2.3.14:

• Re-parse input immediately when encountering parse error. Previously this was only done if the error was actually read which would save us from re-parsing the file (i.e. better performance). However, an error is (a) rare and (b) happens only once per file. Re-parsing on errors does not impact the performance of well formatted files, and a reliable error message is valued more.
• Bugfix: prevent infinite loop on error on input file that contains unicode code points (i.e. any character bigger than 0xC0 usually followed by more bytes).
• Improve error messages for parsers to include parser name and print offending byte(s)

• CSS: remove space after function in property value; margin:calc(10px) calc(20px) => margin:calc(10px)calc(20px)
• SVG: parse A path command correctly when the booleans largeArc and sweep are not separated by a space, such as in A10 10 0 0120 0 which is equivalent to A10 10 0 0 1 20 0
• SVG bugfix: make sure we are processing a valid path command
• SVG bugfix: prevent panic when having insufficient path arguments
• cmd: surpress error when minifying empty directory
• HTML: only minify attributes for known HTML5 tags, fixes #270
• HTML, XML, SVG: minify entities with parse@2.3.13 such as: " => ", " => ", " => ", ’ => ’, ✏ => ✏.

Bugfixes:

• SVG: don't convert polyline/rect/polygon/line to path, which can break CSS, fixes #260
• SVG: relative SVG Bézier commands not properly minified
• CSS: don't remove whitespace in nested unknown at-rules, fixes #262
• CSS: fix panic for background when it contains functions other than calc for background-position, fixes #263
• CSS: fix panic for background-position with three numbers
• CSS: fix panic for url() with only whitespace or only one quote

• Remove import comments
• SVG: do not convert line/rect to path if coordinates are relative percentages
• CSS: fix bug with inline CSS encountering }

• CSS: fix position information in error context
• CSS: fix background-position panic with offsets that are zero
• HTML: trim and collapse whitespace in certain attribute values
• SVG: shorten cubic and quadratic Beziér path data to their shorter format or to line segments

• When minifying floating points, remove trailing zeros and not other numbers
• Make M concurrent-safe
• HTML: keep double quotes around XML-flavour RDFa attributes
• CSS: revert the use of the #RRGGBBAA format as proposed in Color Module Level 4 as it is not yet an official W3C recommendation
• CSS: background-position (also within background) now works with 3 and 4 values as well
• SVG: skipping metadata or rect tags properly even if they are closed by a void tag (like <rect/>)
• SVG pathdata: when cursor doesn't move, don't emit any commands

I'm suspecting that go mod gets confused from a previously reverted v2.3.7 release, so just in case this is a new release that will hopefully fix:

$ go get -u github.com/tdewolff/minify/v2
go: github.com/tdewolff/minify/v2@v2.3.7: go.mod has non-.../v2 module path "github.com/tdewolff/minify" (and .../v2/go.mod does not exist) at revision v2.3.7
go get: error loading module requirements

Add Go modules support by using the github.com/tdewolff/minify/v2 import path.

Important: default mimetype for JavaScript is now application/javascript (it used to be text/javascript).

• HTML bugfix: keep empty value attribute on <input type="radio">, because the default is not an empty string
• HTML bugfix: prevent IE conditional comments from panicking in some instances
• CSS: handle local() for URLs
• CSS: support rgb() and hsl() with spaces instead of commas
• CSS: improve minification for font, background, background-position, background-repeat, background-size, outline and border declarations
• CSS: reintroduce support for IE star-declaration hack
• CSS bugfix: margin and padding now check if values that are functions (such as calc()) are equal and thus eligible for collapsing
• CSS bugfix: parse bad declarations better
• CSS bugfix: add space for attribute selector case insensitivity between the value and i as in input[type="radio" i]
• CSS bugfix: do not collapse outline to 0 but to none
• CSS bugfix: opacity for rgba() and hsla() in CSS2 cannot be rewritten as #rrggbbaa
• SVG bugfix: only use the first pair of coordinates for M to move back to when encountering Z

• CLI: Add bash completion for the minify command
• CLI: improved error messages
• CLI bugfix: don't open all files at once when concatenating, which usually panics when >10000 files are open
• CLI bugfix: don't minify modified files twice when watching them
• Bugfix: prevent panic on long decimals with negative exponent, where rewriting would previously cause longer numbers
• HTML: accept alternative syntax for MS conditional comments
• HTML bugfix: draggable is not a boolean
• HTML bugfix: do not assume mediatype in <meta content="x">
• CSS: add option for CSS2 numbers without exponents
• CSS: trim space in url()
• CSS: minify box-shadow, background and @import better
• CSS bugfix: prevent panic for functions with no arguments or end parenthesis
• CSS bugfix: keep dimensions for zeros in flex property
• CSS bugfix: keep other values for outline and border when width is zero
• CSS bugfix: font normal now handled
• CSS bugfix: add quotes to unquotes url() when we can remove the url function
• CSS bugfix: only omit number dimensions for and
• JS bugfix: ASI behaviour for template literals
• JS bugfix: replace comment as space when comment is removed
• JS bugfix: divide by regular expression
• SVG: don't remove empty groups anymore, as CSS or JS might rely on them
• SVG bugfix: prevent panic on invalid pathdata for arcs