API reference

Break individual words that are wider than maxWidth at grapheme-cluster boundaries. Only applies when maxWidth is set. Defaults to false.

Base direction for text layout. Defaults to 'ltr'. Direction-relative alignment is not derived from it - align stays literal in both directions.

Marker appended to the last kept line under overflow: 'ellipsis'. Defaults to the horizontal ellipsis, U+2026. Set '...' for the three-period spelling, or '' to truncate without a marker. The marker is measured as text in the same font, so a long one eats proportionally more of the line it terminates. Truncation stops at grapheme-cluster boundaries, so a combining sequence or a flag is never cut in half.

Additional gap in pixels between glyphs (on top of the font's advance).

Language tag ('en', 'ja', 'ar-EG') used for Unicode text segmentation - which clusters count as one character, and where a line may break. It selects no font and loads nothing; the platform default locale applies when it is absent.

Vertical boundary in pixels. Only whole lines that fit within it are kept. Has no effect on its own - pair it with an overflow policy.

Hard cap on the number of laid-out lines, counted after wrapping. Unlike maxHeight this clips on its own, whatever overflow says - capping the line count is the whole point of asking for one. Pair it with overflow: 'ellipsis' to mark the last kept line. When both a cap and a maxHeight apply, the smaller one wins. Must be a positive integer.

Word-wrap boundary in pixels. Lines exceeding this width are broken at word boundaries.

What to do with lines that do not fit maxHeight or maxLines. Defaults to 'visible'. - 'visible' - Keep every line; maxHeight is ignored. A maxLines cap still applies, silently. - 'clip' - Drop the lines that do not fit. - 'ellipsis' - Drop them and mark the last visible line with ellipsis, shortening it so it still fits maxWidth when one is set. Under a line cap the marker also reaches a last line that overflows maxWidth with no line dropped at all - a single unbreakable word under maxLines: 1.

How glyph appearance is resolved. Defaults to 'auto'. - 'auto' - use the shared-glyph fast path for content that is safe to render one cluster at a time, and hand anything else to the browser's text engine as a whole line. The classification is deliberately conservative and may admit more content to the fast path over time. - 'simple' - always use the shared glyph cache. The cheapest path and the right one for controlled content; a right-to-left line is reversed cluster by cluster rather than reordered, and contextual scripts render in their isolated forms. - 'browser' - always shape the whole line through the browser, which resolves bidi order and contextual forms. Each line becomes one node-owned raster instead of a run of shared glyphs, so a line whose text changes is rasterized again. A browser-shaped line is one glyph as far as the layout is concerned, so align: 'justify' cannot stretch it and caret geometry resolves to line granularity.

Tab stop spacing, counted in space characters. Defaults to 8, the CSS tab-size initial value. A tab advances the pen to the next multiple of tabSize space widths from the start of its line, so a run of tabs lines columns up instead of adding a fixed gap each. Only reachable under whiteSpace: 'pre'; the collapsing modes turn a tab into a single space before layout runs, as CSS does. Must be a positive finite number. Ignored for browser-shaped lines, which the platform's text engine lays out whole.

Whitespace handling mode: - 'normal' - Consecutive spaces collapse to one; \n becomes a space (standard wrap). - 'pre' - Spaces and newlines preserved verbatim. - 'pre-line' - Spaces collapse; \n preserved (default when no explicit mode). Defaults to 'pre-line' (current historical behaviour).