I am hoping to track the position of the mouse cursor, periodically every t mseconds. So essentially, when a page loads - this tracker should start and for (say) every 100 m
onmousemove = function(e){console.log("mouse location:", e.clientX, e.clientY)}
Open your console (Ctrl+Shift+J), copy-paste the code above and move your mouse on browser window.
ES6 based code:
let handleMousemove = (event) => {
console.log(`mouse position: ${event.x}:${event.y}`);
};
document.addEventListener('mousemove', handleMousemove);
If you need throttling for mousemoving, use this:
let handleMousemove = (event) => {
console.warn(`${event.x}:${event.y}\n`);
};
let throttle = (func, delay) => {
let prev = Date.now() - delay;
return (...args) => {
let current = Date.now();
if (current - prev >= delay) {
prev = current;
func.apply(null, args);
}
}
};
// let's handle mousemoving every 500ms only
document.addEventListener('mousemove', throttle(handleMousemove, 500));
here is example
If just want to track the mouse movement visually:
<!DOCTYPE html>
<html>
<head>
<title></title>
</head>
<style type="text/css">
* { margin: 0; padding: 0; }
html, body { width: 100%; height: 100%; overflow: hidden; }
</style>
<body>
<canvas></canvas>
<script type="text/javascript">
var
canvas = document.querySelector('canvas'),
ctx = canvas.getContext('2d'),
beginPath = false;
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
document.body.addEventListener('mousemove', function (event) {
var x = event.clientX, y = event.clientY;
if (beginPath) {
ctx.lineTo(x, y);
ctx.stroke();
} else {
ctx.beginPath();
ctx.moveTo(x, y);
beginPath = true;
}
}, false);
</script>
</body>
</html>
I don't have enough reputation to post a comment reply, but took TJ Crowder's excellent answer and fully defined the code on a 100ms timer. (He left some details to the imagination.)
Thanks OP for the question, and TJ for the answer! You're both a great help. Code is embedded below as a mirror of isbin.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Example</title>
<style>
body {
height: 3000px;
}
.dot {
width: 2px;
height: 2px;
background-color: black;
position: absolute;
}
</style>
</head>
<body>
<script>
(function() {
"use strict";
var mousePos;
document.onmousemove = handleMouseMove;
setInterval(getMousePosition, 100); // setInterval repeats every X ms
function handleMouseMove(event) {
var eventDoc, doc, body;
event = event || window.event; // IE-ism
// If pageX/Y aren't available and clientX/Y are,
// calculate pageX/Y - logic taken from jQuery.
// (This is to support old IE)
if (event.pageX == null && event.clientX != null) {
eventDoc = (event.target && event.target.ownerDocument) || document;
doc = eventDoc.documentElement;
body = eventDoc.body;
event.pageX = event.clientX +
(doc && doc.scrollLeft || body && body.scrollLeft || 0) -
(doc && doc.clientLeft || body && body.clientLeft || 0);
event.pageY = event.clientY +
(doc && doc.scrollTop || body && body.scrollTop || 0) -
(doc && doc.clientTop || body && body.clientTop || 0 );
}
mousePos = {
x: event.pageX,
y: event.pageY
};
}
function getMousePosition() {
var pos = mousePos;
if (!pos) {
// We haven't seen any movement yet, so don't add a duplicate dot
}
else {
// Use pos.x and pos.y
// Add a dot to follow the cursor
var dot;
dot = document.createElement('div');
dot.className = "dot";
dot.style.left = pos.x + "px";
dot.style.top = pos.y + "px";
document.body.appendChild(dot);
}
}
})();
</script>
</body>
</html>
Irrespective of the browser, below lines worked for me to fetch correct mouse position.
event.clientX - event.currentTarget.getBoundingClientRect().left
event.clientY - event.currentTarget.getBoundingClientRect().top