Regex to Match JavaScript Import Statements

This regex matches various forms of JavaScript ES6 import statements. Here is the token-by-token breakdown:

import — Matches the literal keyword import that begins every ES module import statement.

\s+ — Matches one or more whitespace characters after the import keyword.

(?: — Opens a non-capturing group for the optional import bindings section.

(?:{[^}]}|*\s+as\s+\w+|\w+) — A non-capturing group with three alternatives: named imports in curly braces like {useState, useEffect} matched by {[^}]}, namespace imports like * as utils matched by *\s+as\s+\w+, or default imports like React matched by \w+.

\s*(?:,\s*(?:{[^}]}|*\s+as\s+\w+|\w+)\s)* — Optionally matches additional import bindings separated by commas. This handles combinations like import React, { useState } from.

from\s+ — Matches the literal from keyword followed by whitespace, connecting the bindings to the module specifier.

)? — Makes the entire bindings section optional to support bare imports like import 'polyfill'.

['"][^'"]+['"] — Matches the module specifier string. It starts with a single or double quote, followed by one or more characters that are not quotes (the module path), and ends with a matching quote.

The g flag enables global matching and the m flag enables multiline mode. This pattern covers default imports, named imports, namespace imports, combined imports, and side-effect-only imports. It is useful for dependency analysis, bundler tools, and code refactoring.