clock.js

(function updateClock() { // Update the SVG clock graphic to show current time
    let now = new Date();                       // Current time
    let sec = now.getSeconds();                 // Seconds
    let min = now.getMinutes() + sec/60;        // Fractional minutes
    let hour = (now.getHours() % 12) + min/60;  // Fractional hours
    let minangle = min * 6;                     // 6 degrees per minute
    let hourangle = hour * 30;                  // 30 degrees per hour

    // Get SVG elements for the hands of the clock
    let minhand = document.querySelector("#clock .minutehand");
    let hourhand = document.querySelector("#clock .hourhand");

    // Set an SVG attribute on them to move them around the clock face
    minhand.setAttribute("transform", `rotate(${minangle},50,50)`);
    hourhand.setAttribute("transform", `rotate(${hourangle},50,50)`);

    // Run this function again in 10 seconds
    setTimeout(updateClock, 10000);
}()); // Note immediate invocation of the function here.