Script to load all professors and calculate a department's weighted average for ratings and difficulties.

rateMyProfessorsDeptAvg.js

/** SCORES (RESULTS)
Average rating at Oakland University:     3.12
Average difficulty at Oakland University: 3.56
Based on 123 professors and 4636 ratings in the  Mathematics  department.
https://www.ratemyprofessors.com/search/professors/716?q=*&did=38

Average rating at Oakland Community College:     3.44
Average difficulty at Oakland Community College: 3.35
Based on 14 professors and 132 ratings in the  Mathematics  department.
https://www.ratemyprofessors.com/search/professors/11931?q=*&did=38

Average rating at Macomb Community College (all campuses):     3.46
Average difficulty at Macomb Community College (all campuses): 3.14
Based on 160 professors and 4507 ratings in the  Mathematics  department.
https://www.ratemyprofessors.com/search/professors/1360?q=*&did=38

Average rating at University of Michigan:     3.74
Average difficulty at University of Michigan: 3.42
Based on 474 professors and 4433 ratings in the  Mathematics  department.
https://www.ratemyprofessors.com/search/professors/1258?q=*&did=38

Average rating at Massachusetts Institute of Technology:     4.16
Average difficulty at Massachusetts Institute of Technology: 2.95
Based on 31 professors and 414 ratings in the  Mathematics  department.
https://www.ratemyprofessors.com/search/professors/580?q=*&did=38
*/
// -------------------------------------------------

// Functions
function sleep(ms) {
    return new Promise((resolve) => setTimeout(resolve, ms));
}

// Scroll to bottom
window.scrollTo(0, document.body.scrollHeight);
await sleep(900);

let b = Array.from(document.getElementsByTagName("button")).pop();

// Keep clicking "Show More" til we load all the professors
for (let i = 0; i < 1000; i++) {
    if (Array.from(document.getElementsByTagName("button")).pop().innerText != "Show More") {
        console.info("Done scrolling.");
        break;
    }

    b.click();
    await sleep(900);
    window.scrollTo(0, document.body.scrollHeight);
}

// Aggregate rating elements
let ratings = document.querySelectorAll("[class^=CardNumRating__CardNumRatingNumber]");
let lvlDiffs = document.querySelectorAll("[class^=CardFeedback__CardFeedbackNumber]");
let counts = document.querySelectorAll("[class^=CardNumRating__CardNumRatingCount]");
let l = ratings.length;
let m = lvlDiffs.length;
let n = counts.length;
if (l != n || m != 2 * n) {
    console.error("Different number of ratingValue and ratingCount elements!");
    throw new Error();
}

// Count the totals
let rateTotal = 0.0;
let lvlDiffTotal = 0.0;
let countTotal = 0;
for (let i = 0; i < n; i++) {
    let _r = parseFloat(ratings[i].innerText);
    let _d = parseFloat(lvlDiffs[2 * i + 1].innerText);
    let _c = parseInt(counts[i].innerText.split(" ")[0]);
    rateTotal += _r * _c;
    lvlDiffTotal += _d * _c;
    countTotal += _c;
}

// Print weighted averages
let rateWeight = rateTotal / countTotal;
let lvlDiffWeight = lvlDiffTotal / countTotal;
let deptName = document.querySelector("[class^='SearchResultsHeaderText']").children[0].children[0]
    .innerText;
let schoolName = document.querySelector("[class^='SearchResultsHeaderText']").children[0]
    .children[1].innerText;
console.info(`Average rating ${schoolName}:     ${rateWeight.toFixed(2)}
Average difficulty ${schoolName}: ${lvlDiffWeight.toFixed(2)}
Based on ${n} professors and ${countTotal} ratings ${deptName}.
${window.location.href}`);