Javascript MouseEvent Tutorial with Examples

MouseEvent
Properties & Methods

1. MouseEvent

MouseEvent is an interface that represents for the events occurring when users interact with pointing devices, such as mouse, common events such as click, dbclick, mousedown, mouseup,...

MouseEvent is an sub-interface of UIEvent.

Event types of MouseEvent:

Event	Description
click	The event occurs when the user clicks on an element
contextmenu	The event occurs when the user right-clicks on an element to open a context menu
dblclick	The event occurs when the user double-clicks on an element

mousedown	The event occurs when the user presses a mouse button over an element
mouseup	The event occurs when a user releases a mouse button over an element

mouseenter	The event occurs when the pointer is moved onto an element
mouseleave	The event occurs when the pointer is moved out of an element

mousemove	The event occurs when the pointer is moving while it is over an element or its children.

mouseout	The event occurs when a user moves the mouse pointer out of an element, or out of one of its children
mouseover	The event occurs when the pointer is moved onto an element, or onto one of its children

mousedown, mouseup, click

Let's start with the most common event out of the mouse events that is click. It is formed from pressing down and releasing. The click event is illustrated as below:

dbclick

If you click 2 times quickly, it will create a dbclick event.

mouseover vs mouseenter

The mouseenter event occurs when the cursor enters an element. The mouseover event occurs when the cursor enters an element or one of its child elements.

mouseleave vs mouseout

The mouseleave element occurs when the cursor moves out of an element. The mouseout event happens when the cursor moves out of an element or one of its child elements.

The following example helps you compare mouseenter vs mouseover, mouseleave vs mouseout:

enter-vs-over-leave-vs-out.html

<!DOCTYPE html>
<html>

<head>
    <title>Javascript Mouse Events</title>

    <script src="enter-vs-over-leave-vs-out.js"></script>
    <style>
        #target-div {
            width: 320px;
            height: 150px;
            background: blue;
        }
        #target-div > div  {
            width: 50px;
            height: 80px;
            margin: 40px 0 0 40px;
            padding: 5px 0 0 5px;
            float: left;
            background: yellow;
        }
    </style>
</head>

<body>

    <h3>mouseenter vs mouseover</h3>
    <h3>mouseleave vs mouseout</h3>

    <div id="target-div"
               onmouseenter="mouseenterHandler(event)"
               onmouseover="mouseoverHandler(event)"
               onmouseleave="mouseleaveHandler(event)"
               onmouseout="mouseoutHandler(event)"
               >
            <div>Child</div>
            <div>Child</div>
            <div>Child</div>
    </div>
    <h3>Statistics:</h3>
    <div style="color:red;" id="statistics-div">

    </div>

</body>
</html>

enter-vs-over-leave-vs-out.js

var enterCount = 0;
var overCount = 0;

var leaveCount = 0;
var outCount = 0;


function mouseenterHandler(evt) {
    enterCount += 1;
    showStatistics();
}

function mouseoverHandler(evt) {
    overCount += 1;

    showStatistics();
}


function mouseleaveHandler(evt) {
    leaveCount += 1;
    
    showStatistics();
}

function mouseoutHandler(evt) {
    outCount += 1;

    showStatistics();
}


function showStatistics() {
    var html =
        "enterCount:" + enterCount + "<br/>" //
        +
        "overCount:" + overCount  + "<hr/>" //
        +
        "leaveCount:" + leaveCount + "<br/>" //
        +
        "outCount:" + outCount ;
    document.getElementById("statistics-div").innerHTML = html;
}

mousemove

mousemove-example.html

<!DOCTYPE html>
<html>

<head>
    <title>Javascript Mouse Events</title>

    <script src="mousemove-example.js"></script>
    <style>
        #target-div {
            width: 320px;
            height: 150px;
            background: blue;
            margin-bottom: 50px;
        }
        #target-div > div  {
            width: 50px;
            height: 150px;
            margin: 40px 0 0 40px;
            padding: 5px 0 0 5px;
            float: left;
            background: yellow;
        }
    </style>
</head>

<body>

    <h3>mousemove example</h3>

    <div id="target-div" onmousemove="mousemoveHandler(event)">

            <div>Child</div>
            <div>Child</div>
            <div>Child</div>

    </div>

    <h3>Statistics:</h3>
    <div style="color:red;" id="statistics-div">

    </div>

</body>
</html>

mousemove-example.js

var moveCount = 0;


function mousemoveHandler(evt) {
    moveCount += 1;
    showStatistics();
}


function showStatistics() {
    var html = "moveCount:" + moveCount;
    document.getElementById("statistics-div").innerHTML = html;
}

2. Properties & Methods

MouseEvent is the sub- interface of UIEvent, therefore, it inherits the properties and methods from this interface.

Javascript UiEvent

key

Property	Description
altKey	Returns true if "ALT" key was pressed when the mouse event was triggered, otherwise returns false.
ctrlKey	Returns true if "CTRL" key was pressed when the mouse event was triggered, otherwise returns false.
shiftKey	Returns true if "SHIFT" key was pressed when an event was triggered, otherwise returns false.
metaKey	Returns true if "META" key was pressed when an event was triggered, otherwise returns false.

Example with the ctrlKey property:

prop-ctrlKey-example.html

<!DOCTYPE html>
<html>

<head>
    <title>Javascript Mouse Events</title>

    <style>
        #target-div {
            width: 320px;
            height: 150px;
            background: blue;
            margin-bottom: 10px;
        }
    </style>
    
    <script>
      function clickHandler(evt) {
        var html = "evt.ctrlKey=" + evt.ctrlKey;

        document.getElementById("log-div").innerHTML = html;
      }
    </script>
</head>

<body>

    <h3>Press Ctrl key and Click</h3>

    <div id="target-div" onclick="clickHandler(event)" >

    </div>

    <div style="color:red;" id="log-div">

    </div>

</body>
</html>

Position:

Property	Description
clientX	Returns the horizontal coordinate of the mouse pointer, relative to the current window.
clientY	Returns the vertical coordinate of the mouse pointer, relative to the current window.

offsetX	Returns the horizontal coordinate of the mouse pointer relative to the position of the edge of the target element
offsetY	Returns the vertical coordinate of the mouse pointer relative to the position of the edge of the target element

pageX	Returns the horizontal coordinate of the mouse pointer, relative to the document.
pageY	Returns the vertical coordinate of the mouse pointer, relative to the document.

screenX	Returns the horizontal coordinate of the mouse pointer, relative to the screen (Computer or device)
screenY	Returns the vertical coordinate of the mouse pointer, relative to the screen (Computer or device)

movementX	Returns the horizontal coordinate of the mouse pointer relative to the position of the last mousemove event
movementY	Returns the vertical coordinate of the mouse pointer relative to the position of the last mousemove event

prop-positions-example.html

<!DOCTYPE html>
<html>

<head>
    <title>Javascript Mouse Events</title>

    <script src="prop-positions-example.js"></script>
    <style>
        #target-div {
            width: 300px;
            height: 210px;
            background: #ccc;
            margin: 0px 0px 10px 20px;
            padding: 5px;
        }
    </style>

</head>

<body style="height:450px; width:1000px;">

    <h3>Positions</h3>

    <div id="target-div" onmousemove="mousemoveHandler(event)" >

    </div>

</body>
</html>

prop-positions-example.js

function mousemoveHandler(evt) {

     var html =  "offsetX = " + evt.offsetX +"<br/>"
               + "offsetY = " + evt.offsetY +"<br/>"
               + "clientX = " + evt.clientX +"<br/>"
               + "clientY = " + evt.clientY +"<br/>"
               + "pageX = " + evt.pageX +"<br/>"
               + "pageY = " + evt.pageY +"<br/>"
               + "screenX = " + evt.screenX +"<br/>"
               + "screenY = " + evt.screenY +"<br/>"
               + "movementX = " + evt.movementX +"<br/>"
               + "movementY = " + evt.movementY;

      document.getElementById("target-div").innerHTML = html;
}

button

Property	Description
button	Returns a number that describes which mouse button was pressed when the mouse event was triggered
buttons	Returns a number that describes which mouse buttons were pressed when the mouse event was triggered

~~which~~	(Not a standard property, should not be used).

event.button:

0: Main button, usually the left button or the un-initialized state
1: Auxiliary button, usually the wheel button or the middle button (if present)
2: Secondary button, usually the right button
3: Fourth button, typically the Browser Back button
4: Fifth button, typically the Browser Forward button

event.buttons:

0 : No button or un-initialized
1 : Primary button, usually the left button.
2 : Secondary button, usually the right button.
4 : Auxilary button, usually the mouse wheel button or middle button.
8 : 4th button, typically the "Browser Back" button.
16 : 5th button, typically the "Browser Forward" button.

event.buttons may return a different value other than the above values. For example, event.buttons returns 3 if you press both the left mouse and right mouse at the same time.

prop-button-buttons-example.html

<!DOCTYPE html>
<html>
   <head>
      <title>MouseEvent Example</title>

      <script>
          function mousedownHandler(evt) {
            var logDiv = document.getElementById("log-div");

            logDiv.innerHTML = "event.button= " + evt.button +"<br/>"
                             + "event.buttons= "+ evt.buttons;
          }
      </script>

   </head>
   <body>

      <h3>event.button, event.buttons</h3>

      <button onmousedown="mousedownHandler(event)">Click Me!</button>
      <br/><br/>

      <div id="log-div" style="color:red;"></div>
   </body>
</html>

Other properties

Property	Description
relatedTarget	Returns the element related to the element that triggered the mouse event

Javascript MouseEvent Tutorial with Examples

1. MouseEvent

2. Properties & Methods

ECMAScript, Javascript Tutorials

ECMAScript, Javascript Tutorials

Newest Articles