Slider

From the Base UI reference for Slider and the installed SliderRoot, SliderControl, SliderThumb and SliderValue, and Field's spec for the frame. Slider adds no keys or pointer handling of its own.

The figure stays an <output> with Base UI's aria-live="off": the value is heard from the focused thumb's aria-valuenow or aria-valuetext at every step, so a live figure would say each step a second time, and Base UI keeps it off for that reason. Read in place, it repeats the value the thumb's input says, which a screen reader's reading of the page expects of a control's visible figure.

What axe won't catch, from the contract, each with how this component meets it:

• Everything the eye is told, the ear is told, for every shape each prop accepts: the thumb's place and the figure are the input's aria-valuenow, or its aria-valuetext in the caller's format; a range's two thumbs are named "Minimum" and "Maximum" and each says its own value, never Base UI's English "start range" (CR-7); the description and the error are each thumb's aria-describedby; an invalid slider is aria-invalid and its error is words, never only the thumb's red edge; the sizers, which the eye never sees, are aria-hidden.
• Every landmark and named region has an accessible name: the root's group is named by the field's label, even hidden; Slider is not a landmark.
• Every default label can be overridden: minimumLabel and maximumLabel override "Minimum" and "Maximum", and slotProps.thumb.getAriaLabel names the thumbs in the caller's own words (see Owned strings).
• Every shape the type accepts renders, in every variant: label, description and error render a string, an element and a list alike, by Field; value and defaultValue render one thumb for a number and two for a pair; a long Danish compound in the label or the description wraps, by Field's CR-8, and the figure keeps one line.
• A hidden copy kept for animation is aria-hidden, and a collapsed region is inert: the two sizers, copies of the end figures kept for the figure's width, are aria-hidden and visibility: hidden; nothing collapses.
• Native semantics first: Base UI's native <input type="range"> per thumb, its <output> for the figure, a group round them and Field's native <label>; Perron adds no ARIA beyond three attributes: a range thumb's aria-label through Base UI's getAriaLabel and its aria-valuetext through getAriaValueText (CR-7), and aria-hidden on the two sizers (CR-8).
• Focus moves in reading order and returns on close: each thumb is one tab stop, the lower thumb first, between the label above and the error below; nothing opens or closes.
• Every target is at least size.target-min square: the control is size.target-min tall across the first column, and a press anywhere on it moves the nearest thumb; the thumb, 18 px, sits inside it.
• Loops stop when the system asks for less motion: none here; nothing loops and nothing transitions.

In a range, the two thumbs are named by new owned strings, minimum "Minimum" and maximum "Maximum", given to Base UI's Slider.Thumb through getAriaLabel and overridden by minimumLabel and maximumLabel; and each range thumb's aria-valuetext is its formatted value alone, through getAriaValueText, in place of Base UI's default, which appends the English words "start range" and "end range". Base UI's guidance names each thumb of a range with its own aria-label beside the group's visible label, and the ear hears "Departures per hour, group" then "Minimum, slider, 4"; "Minimum" and "Maximum" fit any quantity, where "From" and "To" fit a time but not a count; Base UI's "start range" is English in every locale, which the owned-strings check would fail in Danish; and a single thumb needs no owned word, since the field's label names it.

Both keys are new, described in en.ts as A range slider: the name of its lower thumb, heard as "Minimum, slider, 4". and A range slider: the name of its upper thumb, heard as "Maximum, slider, 12"., with the Danish, Swedish and Norwegian written by the build.

Every other word is the caller's, through label, description and error, or comes from Intl.NumberFormat in the slider's locale and the caller's format, such as the unit in "1.5 km", or is Base UI's message for a failing check, as Field's spec says.

For a caller using the component, with the reason. Each row is a rule: a must row's Don't is never right, a should row's needs a reason, and Checked by says what catches the Don't in a caller's code.