HORIZON PROJECT

/*!

 * encodeurl

 * Copyright(c) 2016 Douglas Christopher Wilson

 * MIT Licensed

 */

'use strict'

/**

 * Module exports.

 * @public

 */

module.exports = encodeUrl

/**

 * RegExp to match non-URL code points, *after* encoding (i.e. not including "%")

 * and including invalid escape sequences.

 * @private

 */

var ENCODE_CHARS_REGEXP = /(?:[^\x21\x25\x26-\x3B\x3D\x3F-\x5B\x5D\x5F\x61-\x7A\x7E]|%(?:[^0-9A-Fa-f]|[0-9A-Fa-f][^0-9A-Fa-f]|$))+/g

/**

 * RegExp to match unmatched surrogate pair.

 * @private

 */

var UNMATCHED_SURROGATE_PAIR_REGEXP = /(^|[^\uD800-\uDBFF])[\uDC00-\uDFFF]|[\uD800-\uDBFF]([^\uDC00-\uDFFF]|$)/g

/**

 * String to replace unmatched surrogate pair with.

 * @private

 */

var UNMATCHED_SURROGATE_PAIR_REPLACE = '$1\uFFFD$2'

/**

 * Encode a URL to a percent-encoded form, excluding already-encoded sequences.

 *

 * This function will take an already-encoded URL and encode all the non-URL

 * code points. This function will not encode the "%" character unless it is

 * not part of a valid sequence (`%20` will be left as-is, but `%foo` will

 * be encoded as `%25foo`).

 *

 * This encode is meant to be "safe" and does not throw errors. It will try as

 * hard as it can to properly encode the given URL, including replacing any raw,

 * unpaired surrogate pairs with the Unicode replacement character prior to

 * encoding.

 *

 * @param {string} url

 * @return {string}

 * @public

 */

function encodeUrl (url) {

  return String(url)

    .replace(UNMATCHED_SURROGATE_PAIR_REGEXP, UNMATCHED_SURROGATE_PAIR_REPLACE)

    .replace(ENCODE_CHARS_REGEXP, encodeURI)

}