Files
houseplan-card/scripts/css-template-minifier.mjs
Codex 0a0a9f0f4c perf(build): the stylesheet minifier had never run
It looked for the tag written as `css` immediately followed by a
backtick. The plugin is a Rollup transform, so the module has already
been through TypeScript by the time it arrives, and the TS printer puts
a space there: `css `. The guard therefore returned null for every
stylesheet in the project, and minification never ran once — around
23 KB of explanatory comments went to every user in every release.

Matching the tag as a word with optional whitespace turns it on:

  chunk, raw       1 079 508 -> 1 021 115 B   (-58 393)
  initial view     300 111 -> 287 284 B gzip  (-12 816)
  room to the budget   955 -> 13 782 B

The ceiling moves down with the fact, as the tool asks when a graph
shrinks past the band.

The risk is not the two lines; it is that 23 KB of CSS is minified for
the first time. Two witnesses cover it: a browser smoke that puts the
original and the minified text into separate stylesheets and compares
the serialised rules — 1 049 of them, identical up to the whitespace
policy the minifier declares — and a test that takes real comment text
out of src/styles and requires it to be absent from dist, so a plugin
that silently stops working cannot pass again.

Issue: #526
User-Visible: yes
2026-09-11 10:12:13 +03:00

112 lines
3.3 KiB
JavaScript

/**
* Conservative minifier for static Lit css`` templates.
*
* This deliberately is not a general CSS optimiser: it removes comments and
* redundant whitespace while preserving strings, escapes and descendant
* combinators. Interpolated templates fail closed because rewriting across a
* JavaScript expression would make the build depend on runtime values.
*/
const isWhitespace = (char) => /[\t\n\f\r ]/.test(char);
const TIGHT_BEFORE = new Set(['{', '}', ':', ';', ',', '>', ')']);
const TIGHT_AFTER = new Set(['{', '}', ':', ';', ',', '>', '(']);
export function minifyCssText(source, label = '<css>') {
let out = '';
let quote = '';
let pendingSpace = false;
for (let i = 0; i < source.length; i += 1) {
const char = source[i];
const next = source[i + 1];
if (quote) {
out += char;
if (char === '\\') {
if (i + 1 >= source.length) throw new Error(`${label}: dangling CSS escape`);
out += source[++i];
} else if (char === quote) quote = '';
continue;
}
if (char === '"' || char === "'") {
if (pendingSpace && out && !TIGHT_AFTER.has(out.at(-1))) out += ' ';
pendingSpace = false;
quote = char;
out += char;
continue;
}
if (char === '/' && next === '*') {
const end = source.indexOf('*/', i + 2);
if (end < 0) throw new Error(`${label}: unclosed CSS comment`);
i = end + 1;
continue;
}
if (isWhitespace(char)) {
pendingSpace = true;
continue;
}
if (pendingSpace && out && !TIGHT_AFTER.has(out.at(-1)) && !TIGHT_BEFORE.has(char)) {
out += ' ';
}
pendingSpace = false;
if (TIGHT_BEFORE.has(char) && out.endsWith(' ')) out = out.slice(0, -1);
out += char;
}
if (quote) throw new Error(`${label}: unclosed CSS string`);
return out.trim();
}
const CSS_TAG = /(^|[^\w$.])css\s*`/;
export function minifyStaticCssTemplates(code, id = '<module>') {
let cursor = 0;
let output = '';
let changed = false;
while (true) {
const match = CSS_TAG.exec(code.slice(cursor));
if (!match) break;
const start = cursor + match.index + match[1].length;
const tagLength = match[0].length - match[1].length;
let end = start + tagLength;
let escaped = false;
for (; end < code.length; end += 1) {
const char = code[end];
if (escaped) {
escaped = false;
continue;
}
if (char === '\\') {
escaped = true;
continue;
}
if (char === '$' && code[end + 1] === '{') {
throw new Error(`${id}:${end}: interpolated css template is not supported`);
}
if (char === '`') break;
}
if (end >= code.length) throw new Error(`${id}:${start}: unclosed css template`);
const css = code.slice(start + tagLength, end);
output += code.slice(cursor, start);
output += `css\`${minifyCssText(css, `${id}:${start}`)}\``;
cursor = end + 1;
changed = true;
}
if (!changed) return null;
return output + code.slice(cursor);
}
export function cssTemplateMinifier() {
return {
name: 'houseplan-css-template-minifier',
transform(code, id) {
if (!id.endsWith('.ts') || !CSS_TAG.test(code)) return null;
const transformed = minifyStaticCssTemplates(code, id);
return transformed == null ? null : { code: transformed, map: null };
},
};
}