Text alignment is the optional textAlignment attribute of a block: left, center, right or justify. left is the default. Writers omit the key for left, so a block that was never aligned keeps the same attributes and saving it again produces no new ReplaceBlock. Readers treat a missing key, and any value outside the four, as left.

The key matches the editor's textAlignment block prop. Readers apply it to the block's text: paragraphs and headings are aligned. Other block types accept and keep the attribute, but they have no aligned text to show it on yet.

See also

block/paragraph: aligned paragraphs.

block/heading: aligned headings.

block/button alignment: a Button's position in its column, a separate attribute.

Blocks: the block model.