Regular expression tester

I was not too fond of regular expressions, considering them as a strange and mysterious beast. But lately, I've been forced to use all their powers, so I get used to them.

From my experience, if you want to understand regular expressions, you have to find a good description, which I have found in O'Reilly's book "C# 3.0" by Joseph and Ben Albahari. An excellent chapter about regular expressions.

Regular expressions are cool stuff, and all programming languages have implementations of them, and Javascript, which is used to write calculators for this site.

Javascript has a RegExp object, which does the magic.

First, it has method test(string) - which returns true if it finds regular expression in the source text (matched) or false otherwise.

Second, it has method exec(string) - which extracts everything that is matched. It returns an array of results.

Third, and most importantly, we can use RegExp to replace the string by calling source_string.replace(regex, replace_string).

Below is the calculator which allows you to play with regular expressions. You should enter source text, regular expression, modifiers (used in replacement), and replacement expression. After that, you will get calls to test, exec, and replace upon source text.

By default, it extracts all digits which look like phone numbers and formats them.

Regular expressions sandbox

Here is the sample text which contains phone numbers like 1111111, or 2323434, or 5557777, everything is irregular. But they can be translated to regular format, even if they contain only 5 digits, like 77777 or 5-2222

Source text

Regular expression

Modifiers

Replacement expression

Calculate

Result of "test" method

 

Result of "exec" method

 

Result of "replace" method

 

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