# What changed in @chenglou/pretext

> 76 changes in @chenglou/pretext 1 from its official release notes, upgrade guides and advisories: 39 breaking, 8 new APIs and options. Each one cited. Sources checked 2026-10-27. HTML: https://unstale.sh/npm/@chenglou/pretext/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## @chenglou/pretext 1

### Breaking changes

- An atomic rich-inline item's own leading or trailing whitespace no longer creates a gap; a whitespace-only atomic item is an empty box sized by `extraWidth`. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Unrecognized browser layout engines now use Chrome's rules throughout. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- In jsdom and happy-dom, which lack a 2D canvas context, preparing text now throws the missing-Canvas error rather than a TypeError about null. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Chrome now applies text-spacing-trim widths to CJK punctuation pairs and line endings, including across rich-inline item boundaries. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- The npm package no longer includes pages/demos and pages/assets; they remain in the repository. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Passing a font string that Canvas ignores, such as an empty one, now throws a RangeError. (1.0.0) — [release notes](https://github.com/chenglou/pretext/releases/tag/v1.0.0), [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Safari now measures generic font families using the fonts it draws for the page's language. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- `glue` is removed; no-break spaces and word joiners are `text`, and `zero-width-glue` and `control` are added. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- The width argument now precedes the cursor, so callers must swap the second and third arguments. (1.0.0) — [release notes](https://github.com/chenglou/pretext/releases/tag/v1.0.0), [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- The width now precedes the cursor, and the first line is returned without a cursor; swap the second and third arguments at existing calls. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- When the first word exceeds the line width, a following space or zero-width space now ends the line instead of being moved by other content or letter spacing. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Preparing text now throws a `RangeError` when `letterSpacing` is not finite. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Chrome and Firefox no longer add letter spacing after joined-script letters; Safari continues to space each glyph it draws. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Chrome and Firefox now measure text with fi, fl or ffi ligatures as browsers draw it when letter spacing disables those ligatures; Safari remains narrower for this case. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Safari now counts spacing after each glyph it draws in complex text and combining-accent words; measuring glyphs requires additional Canvas calls. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Safari no longer adds letter spacing after U+0085 next-line characters, except next to complex text. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Chrome, Safari and Firefox line-break opportunities now come from ports of each browser's line breaker and data, changing breaks to match browsers in more cases. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Safari now ends lines at U+2028 and U+2029 in normal white space, pre-wrap and rich-inline items. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Negative maxWidth now behaves as zero in plain-text and rich-inline layout; rich-inline widths below 1px also follow the plain-text behavior. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Firefox no longer adds a space for newlines between East Asian characters other than Hangul, or next to East Asian punctuation on ja and zh pages. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Chrome and Firefox no longer add a space for a newline next to a zero-width space in normal white space. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Runs of no-break spaces between other break opportunities now break where they overflow a line, matching browsers. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Runtimes without navigator.userAgent now follow Chrome's rules; outside browsers, measurement uses a global OffscreenCanvas defined before the first prepare(). (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Handles now expose only segments, kinds and widths; callers must change reads of any other handle field. (1.0.0) — [release notes](https://github.com/chenglou/pretext/releases/tag/v1.0.0), [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Handles made by 0.0.9 must not be kept; prepare the text again. (1.0.0) — [release notes](https://github.com/chenglou/pretext/releases/tag/v1.0.0), [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- prepareWithSegments() no longer returns approximate bidi levels per segment; render a paragraph as one DOM element with its direction set to get browser ordering. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- A font string that Canvas ignores, such as an empty one, now throws a RangeError. (1.0.0) — [release notes](https://github.com/chenglou/pretext/releases/tag/v1.0.0)
- Rich-inline line and range cursors no longer index an item's text and are only for passing back to layout functions; use source offsets to find fragment text. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Rich-inline items are laid out as one paragraph: break opportunities come from their joined text, and each item is measured in its own font. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Rich inline accepts `{ width }` boxes for images, emoji, formulas, badges and other inline objects; lines can break before and after a box. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- segLevels is gone; callers that read it must change. (1.0.0) — [release notes](https://github.com/chenglou/pretext/releases/tag/v1.0.0), [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- The locale now controls language-sensitive line breaking and measurement instead of overriding `<html lang>`; omitting it restores the page language, while an empty string means no page language. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Firefox now collapses spaces on both sides of a soft hyphen into one space. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- When a chosen soft-hyphen hyphen does not fit, layout now uses the latest earlier break that fits; Chrome's visible hyphen no longer receives letter spacing. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- In pre-wrap text, tab stops now follow browser behavior, including browser-specific letter-spacing calculations and wrapping of tabs that do not fit. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Firefox treats lone carriage returns and form feeds as zero-width, including at rich-inline item boundaries; CRLF remains one space. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Safari treats a lone carriage return as zero-width in normal white space, with line-ending behavior depending on the text; CRLF remains one space. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- A line containing only soft hyphens before a newline now counts as a line. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Wrapped lines no longer count trailing spaces in their width, and trailing spaces and tabs are measured and kept on lines as browsers lay them out. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)

### New APIs and options

- Rich-inline fragments identify which item owns the collapsed space measured by `gapBefore`, or use -1 when no space precedes the fragment on its line. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Now accepts a `prepare()` handle, avoiding the need to retain every segment string when only line statistics are needed. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Now accepts a `prepare()` handle, avoiding the need to retain every segment string when measuring natural width. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- An options argument with `whiteSpace: 'pre-wrap'` enables CSS pre-wrap behavior across styled runs, including preserved whitespace, line-ending newlines and line-start tab stops. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- An options argument with `wordBreak: 'keep-all'` enables CSS keep-all line breaking for rich-inline paragraphs. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Rich inline lays its items out as one paragraph, as a browser lays out a paragraph’s spans. (1.0.0) — [release notes](https://github.com/chenglou/pretext/releases/tag/v1.0.0)
- Read a fragment’s sourceStart and sourceEnd instead of reading rich-inline cursors as places in an item's text. (1.0.0) — [release notes](https://github.com/chenglou/pretext/releases/tag/v1.0.0), [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Now accepts a `prepare()` handle, avoiding the need to retain every segment string when only line ranges are needed. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)

### Performance

- At a new width, layout is three to six times as fast as in 0.0.9. (1.0.0) — [release notes](https://github.com/chenglou/pretext/releases/tag/v1.0.0)
- Preparing text it has measured before is 1.1 to 13 times as fast as in 0.0.9. (1.0.0) — [release notes](https://github.com/chenglou/pretext/releases/tag/v1.0.0)
- Preparing and measuring rich-inline paragraphs is reported as faster for both new and previously measured paragraphs in the Markdown chat demo. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)

### Behavior and default changes

- Pretext now uses each browser's character rules instead of `Intl.Segmenter`, which remains needed only for text in Southeast Asian scripts written without spaces. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Pretext uses a port of each browser’s own line breaker and data to find line-break opportunities instead of its own rules. (1.0.0) — [release notes](https://github.com/chenglou/pretext/releases/tag/v1.0.0)
- Read a fragment’s sourceStart and sourceEnd instead of reading rich-inline cursors as places in an item's text. (1.0.0) — [release notes](https://github.com/chenglou/pretext/releases/tag/v1.0.0), [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Shared measured-text caches are bounded; after more than 262,144 segments, the next preparation empties them before measuring, while existing handles retain their widths. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)

### Fixes and other changes

- Firefox now breaks around bidi controls as if they were absent, including their effects on line width, spacing and adjacent accents. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Text using a web font split by unicode-range no longer retains a fallback font's space width after preparation without a character from the space's font subset. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Chrome and Firefox on macOS now measure text-font emoji and system-fallback emoji sequences more closely to their drawn widths at small sizes. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Chrome and Firefox on macOS no longer measure U+FE0F after a non-emoji character narrower than the browser draws it at small sizes. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Emoji widths no longer become permanently zero when first prepared while body is display:none, and page CSS no longer skews their measured width. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Chrome now uses fonts for a newly changed html lang value even when the font string is unchanged. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Chrome and Firefox now let ideographic spaces hang past the end of a line instead of wrapping them. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Chrome on macOS now accounts for kana kerning when measuring Japanese lines; name a Japanese font after a font list that Chrome Canvas does not shape as a whole. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Firefox now applies letter spacing in whole increments of 1/60px, matching its layout and preventing small line-wrap discrepancies. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Safari now retains a word's kerning with a following space, both with and without letter spacing. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Chrome line widths now account for kerning between spaces and neighboring words, preventing lines and widest-line-sized bubbles from exceeding Chrome's layout. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Reported line widths are clamped at zero instead of becoming negative, for example under strongly negative letter spacing. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Words wider than a line now account for kerning when choosing cuts, more closely matching Chrome and Firefox; measurements cost more when such a word is first prepared. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Ranges ending past their prepared text now materialize only text up to the range end instead of appending undefined or potentially iterating until memory runs out. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- In Firefox, zero-width break: 'never' items and zero-width boxes that fall past a full line now land on the line Firefox uses. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Rich-inline line-start fragments now begin after spaces and soft hyphens skipped at line starts, including under negative letter spacing. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Rich-inline layout now keeps text or a break: 'never' item on a line when its overflow is within 0.005px, or 1/64px in Safari. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- A line ending at a soft hyphen is measured with U+2010 HYPHEN when the font has one, while the line's text still ends with a hyphen-minus. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Browsers and in-app web views on iPhone, iPad and Mac now use Safari's WebKit wrapping rules; Safari worker preparation uses the same rules as page preparation. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Chrome and Firefox no longer lose text when a URL contains a second www. or scheme before its query. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- Paragraphs made only of zero-width spaces now occupy one line instead of disappearing. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)
- A zero-width space at paragraph or hard-line start no longer disappears when following text wraps. (1.0.0) — [upgrade guide](https://github.com/chenglou/pretext/blob/v1.0.0/CHANGELOG.md)