@remix-run/headers/src/lib/param-values.ts

A toolkit for working with HTTP headers in JavaScript

export function parseParams(
  input: string,
  delimiter: ';' | ',' = ';',
): [string, string | undefined][] {
  // This parser splits on the delimiter and unquotes any quoted values
  // like `filename="the\\ filename.txt"`.
  let parser =
    delimiter === ';'
      ? /(?:^|;)\s*([^=;\s]+)(\s*=\s*(?:"((?:[^"\\]|\\.)*)"|((?:[^;]|\\\;)+))?)?/g
      : /(?:^|,)\s*([^=,\s]+)(\s*=\s*(?:"((?:[^"\\]|\\.)*)"|((?:[^,]|\\\,)+))?)?/g

  let params: [string, string | undefined][] = []

  let match
  while ((match = parser.exec(input)) !== null) {
    let key = match[1].trim()

    let value: string | undefined
    if (match[2]) {
      value = (match[3] || match[4] || '').replace(/\\(.)/g, '$1').trim()
    }

    params.push([key, value])
  }

  return params
}

export function quote(value: string): string {
  if (value.includes('"') || value.includes(';') || value.includes(' ')) {
    return `"${value.replace(/"/g, '\\"')}"`
  }
  return value
}