Insert Google Drive image links as =IMAGE(url) formula

Code.gs

function onOpen() {
  var ui = SpreadsheetApp.getUi();
  ui.createMenu("Insert images")
    .addItem("Insert images", "insertImages")
    .addToUi();
}

/**
 * Scans the J-column of the current sheet, looking for
 * Google Drive file links, getting the download URLs for
 * each file, and then adding the download URL to an =IMAGE(url)
 * formula in adjacent cells to the right of the J-column.
 */
function insertImages() {
  // find and isolate the id chars from a the end of Google Drive file link
  const reFileID = /.+id=(.+)/;

  const sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();

  const [startRowNo, j_ColNo] = [2, 10];
  const lastRowNo = sheet.getLastRow() - startRowNo + 1; // +1 because 1-based row notation

  const j_ColCells = sheet
    .getRange(startRowNo, j_ColNo, lastRowNo, 1)
    .getValues();

  // iterate J-column cells
  j_ColCells.forEach((cell, i) => {
    const currentRowNo = startRowNo + i;

    const links = cell[0].toString().split(",");
    if (links.length === 0) {
      console.error(`row ${currentRowNo}, emtpy links cell`);
      return;
    }

    // iterate links
    links.forEach((link, j) => {
      j += 1; // 1-based column notation

      const nextCol = j_ColNo + j;
      const nextCell = sheet.getRange(currentRowNo, nextCol);

      link = link.trim();
      if (link === "") {
        console.log(
          `(row ${currentRowNo}, link ${j}) appears to be empty`,
        );
        return;
      }

      const m = link.match(reFileID); // m is a match object

      if (!m || m.length !== 2) {
        console.error(
          `(row ${currentRowNo}, link ${j}) could not find "id=..." at end of "${link}"`,
        );
        return;
      }

      const fileID = m[1]; // the id submatch is in the 2nd field of the match object
      const downloadURL = DriveApp.getFileById(fileID).getDownloadUrl();

      if (nextCell.getFormula().includes(downloadURL)) {
        console.log(
          `(row ${currentRowNo}, link ${j}) already has the correct download URL, skipping`,
        );
        return;
      }

      const imageFormula = `=IMAGE("${downloadURL}")`;

      nextCell.setFormula(imageFormula);
    });
  });
}