Parse Response Headers

parseResponseHeaders.js

  /**
   *
   * Parse response header string of the form:
   *
   * "
   *     header: value
   *     another-header: value
   * "
   *
   * @param {string} headerStr    headers to parse
   * @param {boolean} modifyKeys  if true, header keys are modified to be
   *                              camelcase. default: true
   * @return {*}                  object containing header keys
   *
   */
  function parseResponseHeaders( headerStr, modifyKeys ) {
    // no header? return an empty object
    if ( !headerStr ) {
      return {};
    }
    // check if modifyKeys is passed; if not true is the default
    if ( typeof modifyKeys === "undefined" ) {
      modifyKeys = true;
    }
    // split the header string by carraige return, then reduce it to
    // an object containing the header keys and values
    return headerStr.split( "\r\n" ).reduce(
      function parseHeader( prevValue, headerPair ) {
        // header is of the form abc: def; split by ": " and then
        // shift out the key. Reconstruct the value in case some one has
        // a header of abc: def: ghi
        var headerParts = headerPair.split( ": " ),
          headerKey = headerParts.shift(),
          headerValue = headerParts.join( ": " ),
          propParts, prop;
        if ( modifyKeys ) {
          // convert some-property-key to somePropertyKey
          propParts = headerKey.split( "-" );
          prop = propParts.reduce( function ( prevValue, v ) {
            return prevValue + ( v.substr( 0, 1 ).toUpperCase() + v.substr( 1 ) );
          } );
          prop = prop.substr( 0, 1 ).toLowerCase() +
            prop.substr( 1 );
        }
        // if we have one or more part, copy the value to the key
        if ( headerParts.length > 0 ) {
          prevValue[ modifyKeys ? prop : headerKey ] = headerValue;
        } else {
          // otherwise just copy true
          prevValue[ modifyKeys ? prop : headerKey ] = true;
        }
        return prevValue;
      }, {} );
  }