v3.1.0

Added

• react-helmet-async/package.json resolves again. The exports map added in 3.0.0 had left it out.

Changed

• On React 19, mounted <Helmet> instances are merged again, as on React 16–18: the innermost <title> wins and uses the nearest titleTemplate and defaultTitle, and a tag that several <Helmet>s set, such as <meta name="description">, renders once, from the innermost one. Server rendering still outputs every <Helmet>'s tags, because instances only merge once they mount, and when hydrating React reuses only the first server-rendered <title>, so a second one stays in <head>.
• With prioritizeSeoTags, <meta charset> moves from helmet.meta to the start of helmet.priority, because browsers only honor a charset declared within the first 1024 bytes of the document. A template that prints helmet.meta but not helmet.priority no longer outputs it.
• The errors <Helmet> throws for invalid children or a missing <HelmetProvider> are plain Errors, named Error instead of Invariant Violation.

Removed

• The invariant and shallowequal dependencies.

Fixed

• On React 16–18, a <Helmet> with no <HelmetProvider> above it and no helmetData prop throws <Helmet> must be rendered inside a <HelmetProvider> or be given a helmetData prop. If it is, check that only one copy of react-helmet-async is bundled. instead of TypeError: Cannot read properties of undefined (reading 'add').
• On React 16–18, entries in the meta, link, script, style and noscript props that use React attribute names such as itemProp, charSet or httpEquiv are no longer dropped. Their React names are written as HTML attribute names, as for JSX children, so httpEquiv becomes http-equiv and className becomes class in the DOM and in toString().
• <link>, <meta>, <noscript>, <script> and <style> tags inside a fragment are no longer dropped when <Helmet> has more than one fragment, or a fragment next to a tag of the same type.
• On React 16–18, function props such as onLoad are attached as event handlers instead of being written as attributes that contain the function's source, and toString() leaves them out. Handlers receive the native Event, not a React synthetic event.
• lib/index.js and lib/index.esm.js are compiled to ES2018, so webpack 4, which Create React App 3 and 4 use, can parse them. Since 2.0.0 they contained class fields and optional chaining.
• On React 16–18 with defer on (the default), changes made while the tab is in the background are applied within about a second instead of when the tab is shown again.
• A <base> with only a target attribute is no longer dropped. The HTML spec allows href, target, or both.

Full changes: ba5d5fb...v3.1.0