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Regular Expressions

A regular expression (shortened as regex or regexp also referred to as regular expression) is a sequence of characters that specifies a search pattern.

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Your URL Check Passed the Second Line and the Browser Ran the First

Your URL Check Passed the Second Line and the Browser Ran the First

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2 min read
Hot-loading a regex word list from a website into a production API without getting ReDoS'd

Hot-loading a regex word list from a website into a production API without getting ReDoS'd

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7 min read
$10 is a price, $1.9T is a stat: pulling real numbers out of landing pages

$10 is a price, $1.9T is a stat: pulling real numbers out of landing pages

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2 min read
RE2 vs PCRE: Every Regex Construct That Silently Breaks in GA4 (and the Fix)

RE2 vs PCRE: Every Regex Construct That Silently Breaks in GA4 (and the Fix)

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2 min read
A 31-character name froze this Node server for 6 seconds

A 31-character name froze this Node server for 6 seconds

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4 min read
\b became 0x08: the control bytes hiding in our Python regexes

\b became 0x08: the control bytes hiding in our Python regexes

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3 min read
Turning Spoken Commands into Safe Actions: Regex First, the Language Model Second

Turning Spoken Commands into Safe Actions: Regex First, the Language Model Second

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4 min read
Our lastmod ignored a price change: the regex that ate the first figure

Our lastmod ignored a price change: the regex that ate the first figure

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3 min read
The caller's number was a timestamp: picking a phone number out of an Android call notification

The caller's number was a timestamp: picking a phone number out of an Android call notification

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4 min read
A Tiny Regex Bug in Adyen's Java Library, and How My Fix Shipped in SDK v42.0.0

A Tiny Regex Bug in Adyen's Java Library, and How My Fix Shipped in SDK v42.0.0

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3 min read
I tested 6 popular email regexes against 46 addresses. None passed.

I tested 6 popular email regexes against 46 addresses. None passed.

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5 min read
JavaScript regex in practice: greedy vs lazy, lookarounds, and the 300 ms pattern

JavaScript regex in practice: greedy vs lazy, lookarounds, and the 300 ms pattern

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3 min read
How to Learn Regex (and Stop Googling the Same Patterns)

How to Learn Regex (and Stop Googling the Same Patterns)

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5 min read
Your Regex Works in JS but Fails in GA4? Full-Match, RE2, and the Patterns That Actually Work

Your Regex Works in JS but Fails in GA4? Full-Match, RE2, and the Patterns That Actually Work

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2 min read
Stop Trimming \r Off Every Regex Match. .NET 11 Has AnyNewLine

Stop Trimming \r Off Every Regex Match. .NET 11 Has AnyNewLine

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4 min read
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