dist/utils.js
function normalizeHeaderKey() {
  var key = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : '';

  return key.replace(/\r?\n|\r/g, ' ') // no newlines in keys
  .trim().toLowerCase().replace(/^MIME\b|^[a-z]|-[a-z]/ig, function (c) {
    return c.toUpperCase();
  }); // use uppercase words, except MIME
}
function normalizeHeaderKey() {
  var key = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : '';

  return key.replace(/\r?\n|\r/g, ' ') // no newlines in keys
  .trim().toLowerCase().replace(/^MIME\b|^[a-z]|-[a-z]/ig, function (c) {
    return c.toUpperCase();
  }); // use uppercase words, except MIME
}
function normalizeHeaderKey ( ) { var key = arguments . length > 0 && arguments [ 0 ] !== undefined ? arguments [ 0 ] : '' ; return key . replace ( / \r?\n|\r / g , ' ' ) // no newlines in keys . trim ( ) . toLowerCase ( ) . replace ( / ^MIME\b|^[a-z]|-[a-z] / ig , function ( c ) { return c . toUpperCase ( ) ; } ) ; // use uppercase words, except MIME }
Normalizes a header key, uses Camel-Case form, except for uppercase MIME-

@param {String} key Key to be normalized
@return {String} key in Camel-Case form
Normalizes a header key uses Camel - Case form except for uppercase MIME -