Line number of the matched characters in JS/node.js

Question

Is it possible to find the line number of the regex matched characters for multiline inputs (such as files) in Javascript or node.js?

Answer 1

Thank you @Shanimal I changed your code to also add the column position:

function lineNumberByIndex(index, string) {
  const re = /^[\S\s]/gm;
  let line = 0,
    match;
  let lastRowIndex = 0;
  while ((match = re.exec(string))) {
    if (match.index > index) break;
    lastRowIndex = match.index;
    line++;
  }
  return [Math.max(line - 1, 0), lastRowIndex];
}

const findOccurrences = (needle, haystack) => {
  let match;
  const result = [];
  while ((match = needle.exec(haystack))) {
    const pos = lineNumberByIndex(needle.lastIndex, haystack);
    result.push({
      match,
      lineNumber: pos[0],
      column: needle.lastIndex - pos[1] - match[0].length
    });
  }
  return result;
};

const text = `Lorem ipsum dolor sit amet, consectetur adipiscing elit,
sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris
nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.
Excepteur sint occaecat cupidatat non proident,
sunt in culpa qui officia deserunt mollit anim id est laborum.`;
findOccurrences(/dolor/gim, text).forEach(result =>
  console.log(
    `Found: ${result.match[0]} at ${result.lineNumber}:${result.column}`
  )
);