Function getEncodingFromLabel

modules/esm/_encoding/encodingMap.js:271–305

(label)

 * @returns {Encoding | null}
 */
export function getEncodingFromLabel(label) {
    const formattedLabel = trimAsciiWhitespace(label.toLowerCase());

    let canonicalLabel = encodings.get(formattedLabel);

    // Lookup an internal mapping using the canonical name, if found, or
    // the formatted label otherwise.
    //
    // x-mac-ukrainian   >   x-mac-cyrillic   >   MacCyrillic
    //                      (canonical label)    (internal label)
    //
    // big5-hkscs        >   undefined        >   big5-hkscs
    //                      (canonical label)    (internal label)
    //
    let internalLabel = internalEncodings.get(
        canonicalLabel ?? formattedLabel
    );

    // If both the canonical label and the internal encoding
    // are not found, this encoding is unsupported.
    if (!canonicalLabel && !internalLabel)
        return null;

    if (internalLabel) {
        return {
            label: canonicalLabel ?? formattedLabel,
            internalLabel,
        };
    }

    return {
        label: canonicalLabel,
        internalLabel: canonicalLabel,
    };
}