Download CSV and PNG

download.js

/*
 * Copyright 2021 Anthony M. J. O'Hagan
 * MIT License
 */

/**
 * Convert Quasar QTable rows/columns to CSV format string
 * @param {*} columns QTable columns
 * @param {*} rows QTable rows
 * @returns CSV as a string
 */
export function toCsv(columns, rows) {
  const heading = columns.map(c => c.label).join(",");
  return heading + "\n" + rows.map(row => {
    return columns.map(col => {
      let val;
      if (typeof col.field === "string") val = row[col.field];
      else if (typeof col.field === "function") val = col.field(row);
      if (typeof col.format === "function") val = col.format(val);
      if (val === null || typeof val === "undefined") return "";
      val = val.toString();
      // FIXME: Needs a bug fix to check for single quotes in cell values. 
      if (val.includes(",")) return `"${val.replace('"', '""')}"`;
      return val;
    }).join(",");
  }).join("\n");
}

/**
 * Download QTable as a CSV file
 * Requires QTable data to reside in memory (non-virtual)
 * @param {*} filename .csv file name
 * @param {*} columns QTable columns
 * @param {*} rows QTable rows
 * @param {*} disposeAfter dispose
 */
export function csvDownload(filename, columns, rows) {
  var csv = toCsv(columns, rows);
  var blob = new Blob([csv], {type: 'text/csv'});
  // <a href='blob:...' download='myfile.csv' />
  const href = window.URL.createObjectURL(blob);
  const el = document.createElement("a");
  Object.assign(el, { href, download: filename }).click();
  // dispose blob and el after 1 min
  setTimeout(() => { window.URL.revokeObjectURL(href); el.remove(); }, 60000);
}

/**
 * Export and download a Chart / canvas
 * @param {*} filename .png file name
 * @param {*} canvas <canvas> element
 */
export function canvasDownload(filename, canvas) {
  // <a href='blob:...' download='myfile.png' />
  const href = canvas.toDataURL();
  const el = document.createElement("a");
  Object.assign(el, { href, download: filename }).click();
  // dispose blob and el after 1 min
  setTimeout(() => { window.URL.revokeObjectURL(href); el.remove(); }, 60000);
}