Greasy Fork

Revised and Simplified Code

Added another Canvas URL to match

Works on all grade pages

Changed the method of firing the script

// ==UserScript==
// @name         Canvas Grade Calculator
// @namespace    0612
// @version      1.6
// @description  Calculates the Letter Grade for Canvas
// @author       SaturnKai
// @match        http*://*.instructure.com/*
// @match        http*://*.canvas.*.edu/*
// @run-at       document-end
// @grant        none
// ==/UserScript==

function getLetterGrade(percent) {
  let grade = percent.match(/\d+\.?\d+/)?.[0];
  if (!grade || percent.includes("(")) {
    return "";
  }
  if (grade >= 90) {
    return " (A)";
  } else if (grade >= 80) {
    return " (B)";
  } else if (grade >= 70) {
    return " (C)";
  } else if (grade >= 60) {
    return " (D)";
  } else if (grade < 60) {
    return " (F)";
  } else {
    return "";
  }
}

function addLetterGrade(element) {
  element.innerText += getLetterGrade(element.innerText);
}

function main() {
  document.querySelectorAll("td.percent").forEach(addLetterGrade);
  document.querySelectorAll(".final_grade .grade").forEach(addLetterGrade);
}

if (document.readyState === "complete" || document.readyState === "interactive") {
  main();
} else {
  window.addEventListener("DOMContentLoaded", () => {
    main();
  });
}