Regex Recipe: Normalize URL

This recipe describes how to replace multiple slashes in URL & avoid replacing the first // in http:// & https://.

Expected behaviour

To send some concatenated url with multiple slashes and recive the clean one.

Given Input:

http://devcdn.some-hub.net/html5//280131/publish///brand/bundle/games/

Expected Output:

http://devcdn.some-hub.net/html5/280131/publish/brand/bundle/games/

Normalize URL in Java

Preserves // after http:// & https://

    String normalizeURL(String url) {
        return url.replaceAll("(?<!http:|https:)/+/", "/");
    }

Normalize URL in Groovy

Preserves // after : like in in http:// & https://

    String normalizeURL(url) {
        return url.replaceAll(/(?<!:)\/+/, "/");
    }

Normalize URL in JavaScript

"$1" inserts the 1st parenthesized submatch string (/ from //):

    function normalizeURL(url) {
        return url.replace(/([^:]\/)\/+/g, "$1")
    }

## see Also * [Keynote: Regexp Short Notes](http://bloomlab.blogspot.com.ee/2015/10/keynote-regexp-short-notes.html) * [JavaScript API - String replace](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/String/replace) * [Java: Convert JSON to DTO Object](http://bloomlab.blogspot.com.ee/2016/02/java-convert-json-to-dto-object.html) * [Oracle Documentation - Pattern](https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html) * [Keynote: Top JS frmeworks 2015](http://bloomlab.blogspot.com.ee/2015/03/top-javascript-frameworks-2015.html)