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D3.js selection.on() Function

  • Last Updated : 13 Aug, 2020

The d3.selection.on() function in D3.js is used to add a particular event listener to an element. An event may be a string of event type click, mouseover, etc.

Syntax:

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selection.on(typenames[, listener[, options]])

Parameters: This function accepts two parameters as mentioned above and described below:

  • Typename Listener: It is a string event type such as click, submits, etc.
  • Options: This is an optional object that may tell about the special characteristics of the listener.

Note: If a listener is not specified then it returns the currently assigned event for the particular element.



Return Values: This function returns the object.

Below examples illustrate the D3.js selection.on() function in JavaScript:

Example1:

HTML




<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta
            name="viewport"
            path1tent="width=device-width, 
                       initial-scale=1.0"/>
        <title>D3.js selection.on() Function</title>
    </head>
    <style>
        li {
            background-color: green;
            color: #ffffff;
            width: 50px;
            margin-bottom: 5px;
            padding: 20px;
            height: 40px;
        }
        li:hover {
            cursor: pointer;
            opacity: 0.8;
        }
    </style>
    <body>
        <ul>
            <li>Geeks for geeks</li>
            <li>GEEKS FOR GEEKS</li>
        </ul>
        <script src=
        </script>
        <script src=
        </script>
        <script>
            let li = d3.select("li");
            let x = li.on("click", () => {
                console.log("Clicked");
            });
        </script>
    </body>
</html>

Output:

Before clicking on the box:

After clicking on the box:

Example 2:

HTML




<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta
            name="viewport"
            path1tent="width=device-width, 
                       initial-scale=1.0"/>
        <title>D3.js selection.on() Function</title>
    </head>
    <style>
        li {
            background-color: green;
            color: #ffffff;
            width: 100px;
            margin-bottom: 5px;
            padding: 20px;
            height: 50px;
        }
        li:hover {
            cursor: pointer;
            opacity: 0.8;
        }
    </style>
    <body>
        <ul>
            <li>Geeks for geeks</li>
        </ul>
        <script src=
        </script>
        <script src=
        </script>
        <script>
            let li = d3.select("li");
            let x = li.on("mouseover", () => {
                let li = document.querySelector("li");
                li.innerHTML = "mouseOver event";
            });
            // When cursor moves out of the li tag
            x = li.on("mouseout", () => {
                let li = document.querySelector("li");
                li.innerHTML = "Geeks for geeks";
            });
        </script>
    </body>
</html>

Output:

On mouseover:

On mouseout:




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