Remove blank, comment-only or import lines from a JavaScript source file

reduce.js

/**
 * Remove blank, comment-only or import lines from a JavaScript source file.
 *
 * Perfect for getting a quick count of how many actual "content" lines there are in a file.
 *
 * @param {string} javaScript
 * @returns string
 */
function reduce(javaScript) {
  const reduced = javaScript
    .split("\n")
    .filter(
      (line) =>
        line.trim().length !== 0 &&
        !line.trim().startsWith("//") &&
        !line.trim().startsWith("/*") &&
        !line.trim().startsWith("*"),
    );
  const importEndIndex = reduced.findIndex(
    (line) => !line.startsWith("import "),
  );
  return reduced.slice(importEndIndex).join("\n");
}