gistfile1.js

function findPositions(text, query, boundary) {
  let lastBoundary = 0;
  let numMatched = 0;
  let found = false;
  let positions = [];

  for (let pos = 0; pos < text.length; pos++) {
    let c = text[pos];

    if (c == boundary) {
      if (found)
        positions.push({start: lastBoundary + 1, end: pos});

      lastBoundary = pos;
      numMatched = 0;
      found = false;
    } else if (!found) {
      if (c != query[numMatched])
        numMatched = 0;
      else if (++numMatched == query.length)
        found = true;
    }
  }

  if (found)
    positions.push({start: lastBoundary + 1, end: text.length});

  return positions;
}