Regular Expressions in JavaScript – #1 REGEX ULTRA BASICS



A regular expression (or regex) is way to find strings within strings. It’s small code that when applied to a string, will give other strings – either the whole string or parts of the string. This video gives you the ULTRA BASICS of REGEX.

Regexes most common use cases are:
What can we use them for?

1. Validation
If something is formatted correctly. Like verifying if someone has inputted the correct things in a form like an email address or a postal code

2.Extraction
Extract parts of a string that we would like to use. Say find how many times someone wrote “david” in a text.

Replacement
Find all parts of the string with “david” and replace them with something else like “devtips”.

You will learn:
– creating regex in two ways in JavaScript: slash notation or with the constructor new RegExp()
– escaping the special characters
– the special characters and how they work: ^, $, *, +, [a-z], [0-9], w, d for example

Companion code used in the episode

Or try one of these tools to experiment with regexes. They all do basically the same, it’s just a matter of taste:
https://www.regexpal.com/
https://www.regexpal.com/
https://regex101.com/

Read more on MDN, it’s the best resource:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions

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