Regex for Data Extraction and TransformationLesson 6.1

Parsing structured log files with regex

log format anatomy, named groups for log parsing, multiline processing, error level extraction, timestamp normalization, performance on large files

Logs Are Structured Text — Regex Reads Them Perfectly

Most log formats follow a predictable structure. Named groups turn a log line into a typed object in one regex call.

const LOG_RE = /^(?<timestamp>\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}) (?<level>INFO|WARN|ERROR|DEBUG) (?<service>\w+): (?<message>.+)$/;

function parseLine(line) {
  const m = line.match(LOG_RE);
  return m ? m.groups : null;
}