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How to make drag event move in only one direction in javascript?

I'm using drag event for moving an element, but I didn't find a way to make it only move horizontally, it's there any clue for this? Thanks in advance!

There is three steps we need to do
first we get the current mouse x position
second we calculate the distance it has move and the direction by newX = oldX - e.clientX saying subtract old x with current mouse x this way we get something like -3 or 2 or -1 you see we have the distance the direction - or +
Third step we update the element horizontal position by element.style.left = (element.offsetLeft - newX) + "px"
There are more details in the comments in the code. let me know if its not clear
var oldX = 0, newX = 0; // for storing X (horizontal) positions
var element = document.getElementById("mydiv"); // The element you want to drag
// We do the dragging here
function elementDrag(e) {
e = e || window.event;
e.preventDefault();
newX = oldX - e.clientX; // to calculate how much we have moved
oldX = e.clientX; // store current value to use for next move
element.style.left = (element.offsetLeft - newX) + "px"; // update left position
}
// we do this so there is not multiple event handlers
function closeDragElement() {
document.onmouseup = null;
document.onmousemove = null;
}
// when mouse down on element attach mouse move and mouse up for document
// so that if mouse goes outside element still drags
function dragMouseDown(e) {
e = e || window.event;
e.preventDefault();
oldX = e.clientX; // store current value to use for mouse move calculation
document.onmouseup = closeDragElement;
document.onmousemove = elementDrag;
}
element.onmousedown = dragMouseDown;
#mydiv {
position: absolute;
z-index: 9;
background-color: #2196F3;
text-align: center;
border: 1px solid #d3d3d3;
padding: 10px;
cursor: move;
color: #fff;
}
<div id="mydiv">
Click here to move
</div>

Draw a bounding box over an image present inside a modal

I am JavaScript Beginner and I am working on a small code where I have an image displayed inside a Modal and I am trying to draw a bounding box over the image.
I have tried the following code to draw the bounding box over the image.
Html: ( the code for the modal that shows the image)
<div id="myModal" class="modal">
<!-- The Close Button -->
<span class="close">×</span>
<!-- Modal Content (The Image) -->
<div id="imagearea" class="imagearea">
<img class="modal-content" id="img01">
</div>
</div>
Javascript: ( the logic that I tried to draw a bounding box over the image)
initDraw(document.getElementById('imgarea'));
function initDraw(imgarea) {
var mouse = {
x: 0,
y: 0,
startX: 0,
startY: 0
};
function setMousePosition(e) {
var ev = e || window.event; //Moz || IE
if (ev.pageX) { //Moz
mouse.x = ev.pageX + window.pageXOffset;
mouse.y = ev.pageY + window.pageYOffset;
} else if (ev.clientX) { //IE
mouse.x = ev.clientX + document.body.scrollLeft;
mouse.y = ev.clientY + document.body.scrollTop;
}
};
var element = null;
imgarea.onmousemove = function (e) {
setMousePosition(e);
if (element !== null) {
element.style.width = Math.abs(mouse.x - mouse.startX) + 'px';
element.style.height = Math.abs(mouse.y - mouse.startY) + 'px';
element.style.left = (mouse.x - mouse.startX < 0) ? mouse.x + 'px' : mouse.startX + 'px';
element.style.top = (mouse.y - mouse.startY < 0) ? mouse.y + 'px' : mouse.startY + 'px';
}
}
imagearea.onmouseup = function (e) {
if (element !== null) {
element = null;
imagearea.style.cursor = "default";
console.log("finsihed.");
} }
imagearea.onmousedown = function (e) {
if(element==null){
console.log("begun.");
mouse.startX = mouse.x;
mouse.startY = mouse.y;
element = document.createElement('div');
element.className = 'rectangle'
element.style.left = mouse.x + 'px';
element.style.top = mouse.y + 'px';
imagearea.appendChild(element)
imagearea.style.cursor = "crosshair";
e.preventDefault();
}
}
}
css: (for the bounding box)
.rectangle {
border: 10px solid red;
position: absolute;
}
.imagearea {
display: flex;
flex-direction: column;
float: left;
width: 35%;
max-width: 700px;
position: relative;
}
#img01{
position: absolute;
}
The above code displays the image in modal and when I try to draw the bounding box on the image, the cursor changes to crosshair as expected , but I could not see the bounding box when i draw it over the image. Just the cursor changes but the rectangle(bounding box) which I draw over the image is not visible.
Can some one help me with this. Thank you

There are two problems.
You can't append children to <img>.
Your calculations are based on the viewport, while border's CSS is relative to the image. There are multiple ways to fix that, the quickest one would be to subtract image's position from your mouse position, like this:
function setMousePosition(e) {
// your mouse calculations
const boundaries = e.currentTarget.getBoundingClientRect();
mouse.x -= boundaries.left;
mouse.y -= boundaries.top;
}
Also, make sure you use setMousePosition() in your mousedown handler.

drag and drop div element work well on element one, but element 2 not well

I've created a simple code to drag and drop two div elements but work well on div 1 but div 2 not work well.
The mouse cursor not Standing on div 2 correctly.
Please check the online demo link in the bottom of the question.
HTML
<div class="draggable"></div>
<div class="draggable"></div>
CSS
div.draggable {
background-color:yellowgreen;
width:150px;
height:100px;
border:1px solid #ffff66;
position:relative;
}
JavaScript
var element = null;
var elemPosL = 0;
var elemPosT = 0;
var isMouseDown = false;
document.onmousedown = function(e) {
element = e.target;
if (element.className === "draggable") {
elemPosL = e.clientX - element.offsetLeft;
elemPosT = e.clientY - element.offsetTop;
isMouseDown = true;
}
};
document.onmousemove = function(e) {
if (isMouseDown) {
element.style.left = e.clientX - elemPosL + "px";
element.style.top = e.clientY - elemPosT + "px";
}
};
document.onmouseup = function() {
isMouseDown = false;
element = null;
};
You can see online

Using position: absolute; fixes it.
If you want relative, check Implementing drag and drop on relatively positioned elements in JavaScript

Javascript - Track mouse position

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 ms, I should get the new value of posX and posY and print it out in the form.
I tried the following code - but the values do not get refreshed - only the initial values of posX and posY show up in the form boxes. Any ideas on how I can get this up and running ?
<html>
<head>
<title> Track Mouse </title>
<script type="text/javascript">
function mouse_position()
{
var e = window.event;
var posX = e.clientX;
var posY = e.clientY;
document.Form1.posx.value = posX;
document.Form1.posy.value = posY;
var t = setTimeout(mouse_position,100);
}
</script>
</head>
<body onload="mouse_position()">
<form name="Form1">
POSX: <input type="text" name="posx"><br>
POSY: <input type="text" name="posy"><br>
</form>
</body>
</html>

The mouse's position is reported on the event object received by a handler for the mousemove event, which you can attach to the window (the event bubbles):
(function() {
document.onmousemove = handleMouseMove;
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 );
}
// Use event.pageX / event.pageY here
}
})();
(Note that the body of that if will only run on old IE.)
Example of the above in action - it draws dots as you drag your mouse over the page. (Tested on IE8, IE11, Firefox 30, Chrome 38.)
If you really need a timer-based solution, you combine this with some state variables:
(function() {
var mousePos;
document.onmousemove = handleMouseMove;
setInterval(getMousePosition, 100); // setInterval repeats every X ms
function handleMouseMove(event) {
var dot, eventDoc, doc, body, pageX, pageY;
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
}
else {
// Use pos.x and pos.y
}
}
})();
As far as I'm aware, you can't get the mouse position without having seen an event, something which this answer to another Stack Overflow question seems to confirm.
Side note: If you're going to do something every 100ms (10 times/second), try to keep the actual processing you do in that function very, very limited. That's a lot of work for the browser, particularly older Microsoft ones. Yes, on modern computers it doesn't seem like much, but there is a lot going on in browsers... So for example, you might keep track of the last position you processed and bail from the handler immediately if the position hasn't changed.

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.

Here's a solution, based on jQuery and a mouse event listener (which is far better than a regular polling) on the body:
$("body").mousemove(function(e) {
document.Form1.posx.value = e.pageX;
document.Form1.posy.value = e.pageY;
})

What I think that he only wants to know the X/Y positions of cursor than why answer is that complicated.
// Getting 'Info' div in js hands
var info = document.getElementById('info');
// Creating function that will tell the position of cursor
// PageX and PageY will getting position values and show them in P
function tellPos(p){
info.innerHTML = 'Position X : ' + p.pageX + '<br />Position Y : ' + p.pageY;
}
addEventListener('mousemove', tellPos, false);
* {
padding: 0:
margin: 0;
/*transition: 0.2s all ease;*/
}
#info {
position: absolute;
top: 10px;
right: 10px;
background-color: black;
color: white;
padding: 25px 50px;
}
<!DOCTYPE html>
<html>
<body>
<div id='info'></div>
</body>
</html>

I believe that we are overthinking this,
function mouse_position(e)
{
//do stuff
}
<body onmousemove="mouse_position(event)"></body>

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

Just a simplified version of #T.J. Crowder and #RegarBoy's answers.
Less is more in my opinion.
Check out onmousemove event for more info about the event.
There's a new value of posX and posY every time the mouse moves according to the horizontal and vertical coordinates.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Example Mouse Tracker</title>
<style>
body {height: 3000px;}
.dot {width: 2px;height: 2px;background-color: black;position: absolute;}
</style>
</head>
<body>
<p>Mouse tracker</p>
<script>
onmousemove = function(e){
//Logging purposes
console.log("mouse location:", e.clientX, e.clientY);
//meat and potatoes of the snippet
var pos = e;
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>

if anyone still looking for answer then,
function track(e) {
console.log("X - ", e.pageX, " Y - ", e.pageY);
}
addEventListener("mousemove", track, false);
paste this code in console to see immediate action

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>

document.addEventListener('mousemove', (event) => {
document.getElementById("line").style.top = event.clientY - 10 + 'px';
document.getElementById("lineY").style.left = event.clientX - 10 + 'px';
document.getElementById("pos").style.top = (event.clientY - 60) + 'px';
document.getElementById("pos").style.left = (event.clientX - 60) + 'px';
});
body {
position: relative;
height: auto;
min-height: 100% !important;
background-color: lightblue;
}
h1 {
color: white;
text-align: center;
}
p {
font-family: verdana;
font-size: 20px;
}
.abs {
position: relative;
}
.lineY {
display: flex;
position: relative;
left: 0px;
background-color: black;
width: 2px;
height: 100vh;
min-height: 100%
}
.line {
display: flex;
position: relative;
background-color: black;
min-height: 2px;
width: 100%;
}
.circle {
display: flex;
position: absolute;
left: 0px;
top: 0px;
}
<div class='line' id="line"></div>
<div class='lineY' id="lineY"></div>
<svg height="100" width="100" id="pos" class="circle">
<circle cx="50" cy="50" r="40" stroke="black" stroke-width="3" fill="transparent" />
</svg>

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

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>

Here is a solution
document.onmousemove = showCoords;
function showCoords(event) {
var x = event.clientX;
var y = event.clientY;
var coords = "X coords: " + x + ", Y coords: " + y;
document.getElementById("box1").innerHTML = coords;
}

[...document.querySelectorAll("*")].forEach(h => h.addEventListener("mousemove", function(event) {
console.table({
"mouse x": event.clientX,
"mouse y": event.clientY
});
}));

Here is the simplest way to track your mouse position
Html
<body id="mouse-position" ></body>
js
document.querySelector('#mouse-position').addEventListener('mousemove', (e) => {
console.log("mouse move X: ", e.clientX);
console.log("mouse move X: ", e.screenX);
}, );
know more

This is the shortest way to get the coordinates of mouse pointer.
Just put your element where cursor is going to hover, inside $("")
$("***enter you element here***").mousemove(function(event)
{
console.clear()
var x = event.originalEvent.screenX;
var y = event.originalEvent.screenY;
console.log("x : "+x)
console.log("y : "+y)
})

Here’s a combination of the two requirements: track the mouse position, every 100 milliseconds:
var period = 100,
tracking;
window.addEventListener("mousemove", function(e) {
if (!tracking) {
return;
}
console.log("mouse location:", e.clientX, e.clientY)
schedule();
});
schedule();
function schedule() {
tracking = false;
setTimeout(function() {
tracking = true;
}, period);
}
This tracks & acts on the mouse position, but only every period milliseconds.

We recently had to find the current x,y position to enumerate elements over which the cursor is hovering independent of z-index. We ended up just attaching a mousemove event listener to document e.g.,
function findElements(e) {
var els = document.elementsFromPoint(e.clientX, e.clientY);
// do cool stuff with els
console.log(els);
return;
}
document.addEventListener("mousemove", findElements);

Make an image follow mouse pointer

I need a rocket to follow the movements of the mouse pointer on my website. This means it should rotate to face the direction of motion, and if possible, accelerate depending on the distance it has to cover.
Is this even possible ? jquery perhaps ?

by using jquery to register .mousemove to document to change the image .css left and top to event.pageX and event.pageY.
example as below
http://jsfiddle.net/BfLAh/1/
$(document).mousemove(function(e) {
$("#follow").css({
left: e.pageX,
top: e.pageY
});
});
#follow {
position: absolute;
text-align: center;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="follow"><img src="https://placekitten.com/96/140" /><br>Kitteh</br>
</div>
updated to follow slowly
http://jsfiddle.net/BfLAh/3/
for the orientation , you need to get the current css left and css top and compare with event.pageX and event.pageY , then set the image orientation with
-webkit-transform: rotate(-90deg);
-moz-transform: rotate(-90deg);
for the speed , you can set the jquery .animation duration to certain amount.

Ok, here's a simple box that follows the cursor
Doing the rest is a simple case of remembering the last cursor position and applying a formula to get the box to move other than exactly where the cursor is. A timeout would also be handy if the box has a limited acceleration and must catch up to the cursor after it stops moving. Replacing the box with an image is simple CSS (which can replace most of the setup code for the box). I think the actual thinking code in the example is about 8 lines.
Select the right image (use a sprite) to orientate the rocket.
Yeah, annoying as hell. :-)
function getMouseCoords(e) {
var e = e || window.event;
document.getElementById('container').innerHTML = e.clientX + ', ' +
e.clientY + '<br>' + e.screenX + ', ' + e.screenY;
}
var followCursor = (function() {
var s = document.createElement('div');
s.style.position = 'absolute';
s.style.margin = '0';
s.style.padding = '5px';
s.style.border = '1px solid red';
s.textContent = "🚀"
return {
init: function() {
document.body.appendChild(s);
},
run: function(e) {
var e = e || window.event;
s.style.left = (e.clientX - 5) + 'px';
s.style.top = (e.clientY - 5) + 'px';
getMouseCoords(e);
}
};
}());
window.onload = function() {
followCursor.init();
document.body.onmousemove = followCursor.run;
}
#container {
width: 1000px;
height: 1000px;
border: 1px solid blue;
}
<div id="container"></div>

Here's my code (not optimized but a full working example):
<head>
<style>
#divtoshow {position:absolute;display:none;color:white;background-color:black}
#onme {width:150px;height:80px;background-color:yellow;cursor:pointer}
</style>
<script type="text/javascript">
var divName = 'divtoshow'; // div that is to follow the mouse (must be position:absolute)
var offX = 15; // X offset from mouse position
var offY = 15; // Y offset from mouse position
function mouseX(evt) {if (!evt) evt = window.event; if (evt.pageX) return evt.pageX; else if (evt.clientX)return evt.clientX + (document.documentElement.scrollLeft ? document.documentElement.scrollLeft : document.body.scrollLeft); else return 0;}
function mouseY(evt) {if (!evt) evt = window.event; if (evt.pageY) return evt.pageY; else if (evt.clientY)return evt.clientY + (document.documentElement.scrollTop ? document.documentElement.scrollTop : document.body.scrollTop); else return 0;}
function follow(evt) {
var obj = document.getElementById(divName).style;
obj.left = (parseInt(mouseX(evt))+offX) + 'px';
obj.top = (parseInt(mouseY(evt))+offY) + 'px';
}
document.onmousemove = follow;
</script>
</head>
<body>
<div id="divtoshow">test</div>
<br><br>
<div id='onme' onMouseover='document.getElementById(divName).style.display="block"' onMouseout='document.getElementById(divName).style.display="none"'>Mouse over this</div>
</body>