Reading and writing regular expressions for sane people

1.do-it-yourself.js

var parse_url = /^(?:([A-Za-z]+):)?(\/{0,3})(0–9.\-A-Za-z]+)(?::(\d+))?(?:\/([^?#]*))?(?:\?([^#]*))?(?:#(.*))?$/;

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2.intention-explained.js

// parse a url, only capture the host part
// eg. protocol://host
//     protocol://host:port/path?querystring#anchor
//     host
//     host/path
//     host:port/path
//     protocol://host:port/path?querystring#anchor
var parse_url = /^(?:([A-Za-z]+):)?(\/{0,3})(0–9.\-A-Za-z]+)(?::(\d+))?(?:\/([^?#]*))?(?:\?([^#]*))?(?:#(.*))?$/;

...

3.human-readable.js

// parse a url, only capture the host part
//   (?:([A-Za-z]+):)?
//     protocol — an optional alphabetic protocol followed by a colon
//   (\/{0,3})(0–9.\-A-Za-z]+)
//     host — 0–3 forward slashes followed by alphanumeric characters
//   (?::(\d+))?
//     port — an optional colon and a sequence of digits
//   (?:\/([^?#]*))?
//     path — an optional forward slash followed by any number of
//     characters not including ? or #
//   (?:\?([^#]*))?
//     query string — an optional ? followed by any number of
//     characters not including #
//   (?:#(.*))?
//     anchor — an optional # followed by any number of characters
var parse_url = /^(?:([A-Za-z]+):)?(\/{0,3})(0–9.\-A-Za-z]+)(?::(\d+))?(?:\/([^?#]*))?(?:\?([^#]*))?(?:#(.*))?$/;

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