javascript - Confetti animation only appearing on the lower half

var maxParticleCount = 150; //set max confetti count
var particleSpeed = 2; //set the particle animation speed
var startConfetti; //call to start confetti animation
var stopConfetti; //call to stop adding confetti
var toggleConfetti; //call to start or stop the confetti animation depending on whether it's already running
var removeConfetti; //call to stop the confetti animation and remove all confetti immediately

(function() {
    startConfetti = startConfettiInner;
    stopConfetti = stopConfettiInner;
    toggleConfetti = toggleConfettiInner;
    removeConfetti = removeConfettiInner;
    var colors = ["DodgerBlue", "OliveDrab", "Gold", "Pink", "SlateBlue", "LightBlue", "Violet", "PaleGreen", "SteelBlue", "SandyBrown", "Chocolate", "Crimson"]
    var streamingConfetti = false;
    var animationTimer = null;
    var particles = [];
    var waveAngle = 0;
    
    function resetParticle(particle, width, height) {
        particle.color = colors[(Math.random() * colors.length) | 0];
        particle.x = Math.random() * width;
        particle.y = Math.random() * height - height;
        particle.diameter = Math.random() * 10 + 5;
        particle.tilt = Math.random() * 10 - 10;
        particle.tiltAngleIncrement = Math.random() * 0.07 + 0.05;
        particle.tiltAngle = 0;
        return particle;
    }

    function startConfettiInner() {
        var width = window.innerWidth;
        var height = window.innerHeight;
        window.requestAnimFrame = (function() {
            return window.requestAnimationFrame ||
                window.webkitRequestAnimationFrame ||
                window.mozRequestAnimationFrame ||
                window.oRequestAnimationFrame ||
                window.msRequestAnimationFrame ||
                function (callback) {
                    return window.setTimeout(callback, 16.6666667);
                };
        })();
        var canvas = document.getElementById("confetti-canvas");
        if (canvas === null) {
            canvas = document.createElement("canvas");
            canvas.setAttribute("id", "confetti-canvas");
            canvas.setAttribute("style", "display:block;z-index:999999;pointer-events:none");
            document.body.appendChild(canvas);
            canvas.width = width;
            canvas.height = height;
            window.addEventListener("resize", function() {
                canvas.width = window.innerWidth;
                canvas.height = window.innerHeight;
            }, true);
        }
        var context = canvas.getContext("2d");
        while (particles.length < maxParticleCount)
            particles.push(resetParticle({}, width, height));
        streamingConfetti = true;
        if (animationTimer === null) {
            (function runAnimation() {
                context.clearRect(0, 0, window.innerWidth, window.innerHeight);
                if (particles.length === 0)
                    animationTimer = null;
                else {
                    updateParticles();
                    drawParticles(context);
                    animationTimer = requestAnimFrame(runAnimation);
                }
            })();
        }
    }

    function stopConfettiInner() {
        streamingConfetti = false;
    }

    function removeConfettiInner() {
        stopConfetti();
        particles = [];
    }

    function toggleConfettiInner() {
        if (streamingConfetti)
            stopConfettiInner();
        else
            startConfettiInner();
    }

    function drawParticles(context) {
        var particle;
        var x;
        for (var i = 0; i < particles.length; i++) {
            particle = particles[i];
            context.beginPath();
            context.lineWidth = particle.diameter;
            context.strokeStyle = particle.color;
            x = particle.x + particle.tilt;
            context.moveTo(x + particle.diameter / 2, particle.y);
            context.lineTo(x, particle.y + particle.tilt + particle.diameter / 2);
            context.stroke();
        }
    }

    function updateParticles() {
        var width = window.innerWidth;
        var height = window.innerHeight;
        var particle;
        waveAngle += 0.01;
        for (var i = 0; i < particles.length; i++) {
            particle = particles[i];
            if (!streamingConfetti && particle.y < -15)
                particle.y = height + 100;
            else {
                particle.tiltAngle += particle.tiltAngleIncrement;
                particle.x += Math.sin(waveAngle);
                particle.y += (Math.cos(waveAngle) + particle.diameter + particleSpeed) * 0.5;
                particle.tilt = Math.sin(particle.tiltAngle) * 15;
            }
            if (particle.x > width + 20 || particle.x < -20 || particle.y > height) {
                if (streamingConfetti && particles.length <= maxParticleCount)
                    resetParticle(particle, width, height);
                else {
                    particles.splice(i, 1);
                    i--;
                }
            }
        }
    }
})();Copy code

<!DOCTYPE html>
<html>
 <head>
     <!--emoji-->
    <meta charset="UTF-8"> 
    <!--title-->
    <title>&#127881;Happy Birthday&#127881;</title>
    <!--animation-->
    <link type="text/css" rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/3.5.2/animate.min.css">
    <!--favicon-->
    <link rel="icon" type="image/x-icon" href="Images/favicon.ico">
    <link href='https://fonts.googleapis.com/css?family=Raleway' rel='stylesheet'>
    <!--confetti animation-->
    <script src="confetti.js"></script>
    <!--CSS-->
<style>

</style> 
</head> 

<body style="background-color:#06589c; width: 100%; height: 100%;">
       <!-- Confetti  JS-->
    <script>

        // start

        const start = () => {
            setTimeout(function() {
                startConfetti();
            }, 1); // 1000 is time that after 1 second start the confetti ( 1000 = 1 sec)
        };

        //  Stop

        const stop = () => {
            setTimeout(function() {
                stopConfetti();
            }, 3000); // 5000 is time that after 5 second stop the confetti ( 5000 = 5 sec)
        };

        start();
        stop();
    </script>
     <div class="animated pulse infinite" style="font-size: 75px; color: white; font-family: 'Raleway'; margin-top: 30px; margin-left: 75px; margin-bottom: 10px; font-weight: bold;">Dear Eshal,</div>
     <div class="animated pulse infinite" style="font-size: 100px; color: white; font-family:'Raleway'; text-align: center; margin-top: 55px; font-weight: bold;">Happy Birthday!</div>
     <div class="Birthday Cake" style="text-align: center;">
     <img src="images/favicon.png" width="346.4px" height="310.8px" alt="Birthday Cake">
     </div>
     
 </body>
</html>Copy code