@nestjs/platform-express/adapters/utils/get-media-type-version.util.js

Nest - modern, fast, powerful node.js web framework (@platform-express)

/**
 * Returns the version carried by an `Accept` header for media type versioning,
 * e.g. `2` for `application/json;v=2` with the `v=` key.
 *
 * The version parameter may follow other parameters and may belong to any
 * media range of a list (`text/html, application/json;v=2`); the first match
 * wins. Returns `undefined` when no parameter starts with the key.
 *
 * Duplicated in each platform package so that a platform package never
 * depends on a newer `@nestjs/core` than the one installed.
 */
export function getMediaTypeVersion(acceptHeader, key) {
    const mediaRanges = []
        .concat(acceptHeader ?? [])
        .flatMap(value => value.split(','));
    for (const mediaRange of mediaRanges) {
        const [, ...parameters] = mediaRange.split(';');
        for (const parameter of parameters) {
            const trimmedParameter = parameter.trim();
            if (trimmedParameter.startsWith(key)) {
                return trimmedParameter.slice(key.length);
            }
        }
    }
    return undefined;
}