Accessible Name

accname implements Accessible Name and Description Computation 1.2 and the naming rules from HTML-AAM 1.0, generic over the document model from a11y-dom. It is written against the specification, not against an existing implementation; the step numbers in the source match those of the normative text.

use a11y_dom::{elements, Arena, Document, Node};
use accname::{name, IdIndex};

let doc = Arena::builder()
    .open("form")
        .open("span").attr("id", "l").text("First name").close()
        .open("input").attr("id", "v").attr("aria-labelledby", "l").close()
    .close()
    .build();

let ids = IdIndex::build(doc.root());
let field = elements(&doc).find(|n| n.local_name() == "input").unwrap();
assert_eq!(name(field, &ids).as_deref(), Some("First name"));

Why this cannot be done in passing

An approximation made of “subtree text plus aria-label” is wrong in exactly the cases where it matters:

• aria-labelledby resolves reference chains and may draw on nodes that are otherwise hidden.
• An embedded control contributes its value within a recursion, not its label.
• For roles such as generic or paragraph, a name is prohibited.

What is covered

Steps 2A to 2I: aria-labelledby with reference chains and cycle protection, aria-label, the native HTML text alternatives (alt, label via for and wrapping, legend, caption, figcaption, title in SVG, the special cases of input), embedded controls, name from content, title as the last fallback.

Plus role computation per HTML-AAM with the context-dependent cases: header and footer are landmarks only outside sectioning elements, section is a region only when named, an img with empty alt is presentation.

The public API

Function	Purpose
name, description	Accessible name and description of a node
role	the effective role, explicit or implicit
implicit	the implicit role per HTML-AAM
allows_name_from_content, name_is_prohibited	properties of a role
IdIndex	ID index for references, built once per document

The detailed documentation is on docs.rs/accname.

Limit without rendering

Step 2A excludes hidden nodes. Without rendering data, only aria-hidden="true" and the hidden attribute are detectable, display: none and visibility: hidden are not. A host with Rendering can be more precise here; the crate deliberately stays with what is decidable without layout.