MAIDR JavaScript API
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    Function tagLayerElements

    • Finds the Victory data elements inside a container for a given layer, tags them with a unique data attribute, and returns the CSS selector that matches exactly those elements.

      Strategy:

      1. Victory renders each data component's elements with role="presentation" on the individual data shapes.
      2. We query for the expected SVG tag (e.g. rect for bars) that carries role="presentation".
      3. We skip elements that belong to other layers by tracking which elements were already claimed.
      4. Each claimed element receives a data-maidr-victory-<layerIndex> attribute so MAIDR can select them deterministically.

      Parameters

      • svg: SVGElement

        The panel's root svg element

      • layer: VictoryLayerInfo

        The extracted layer info

      • layerIndex: number

        Numeric index for generating unique attribute names

      • claimed: Set<Element>

        Set of elements already claimed by prior layers of the same panel (must not be shared across panels)

      • scope: string

        Per-chart (and, in multi-panel mode, per-panel) CSS scope prefix that names this panel's elements alone

      • panelIndex: number | null = null

        Panel index in multi-panel mode; null keeps the original single-panel attribute naming

      Returns string | string[] | CandlestickSelector | BoxSelector[] | string[][] | undefined

      Whatever names this layer's marks: one CSS selector for a series the model can walk positionally, a string[] when the marks have to be named one by one, a string[][] grid naming each segment of a stack, or the structured selector a box or a candle needs. undefined if the elements could not be matched, in which case highlighting degrades gracefully.

      This relies on Victory's role="presentation" attribute on data elements, which is a stable Victory convention (tested with v37). If Victory changes this convention, selector tagging will silently degrade and highlighting will stop working (audio/text/braille are unaffected).

      The emitted selectors are prefixed with scope (e.g. #<containerId> , or #<containerId> [data-maidr-victory-panel="i"] in multi-panel mode) so that they cannot match another Victory chart's identically-indexed tags wherever they are read, nor another panel's: the panels share the chart MAIDR resolves them in. The per-element tag attributes only need to be unique within their own container, which scope plus the panel-folded names guarantee.

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