Unminification

This is an SWC plugin which aims to reverse many of the effects of code minification.

Setup

• use Rust nightly: rustup override set nightly
• run: rustup target add wasm32-wasi
• build using: cargo build-wasi --release

Changes

Restore Literals

• SWC and other transpilers transform literals into equivalent values to reduce the size of code generated
• The following are reverted back into their literal forms:
  • !0 ➞ true
  • !1 ➞ false
  • void 0 ➞ undefined
  • 1 / 0 ➞ Infinity
  • -1 / 0 ➞ -Infinity
  • 0 / 0 ➞ NaN
• Note that: undefined, Infinity, and NaN could be potentially inaccurate since they are not reserved words. However this is unlikely to be a concern in a minified context.

Desequencing

• Transpilers often convert a sequence of statements into a sequence expression to save space

- foo(), bar();
+ foo();
+ bar();

- foo = (baz(), bar);
+ baz();
+ foo = bar;

- return (foo(), bar)
+ foo();
+ return bar;

- throw (foo(), bar)
+ foo();
+ throw bar;

- if ((foo = bar, baz)) {}
+ foo = bar;
+ if (baz) {}

- switch (foo(), bar) {}
+ foo();
+ switch(bar) {}

# add normal for

- for (foo in (baz(), bar)) {}
+ baz();
+ for (foo in bar) {}

- for (foo of (baz(), bar)) {}
+ baz();
+ for (foo of bar) {}