D3.JS (Data Driven Documents)
Last Updated : 30 Sep, 2024
What is D3.js?
D3, short for Data-Driven Documents, is a powerful JavaScript library designed for manipulating documents based on data. It's one of the most effective frameworks for data visualization, enabling developers to create dynamic, interactive visualizations in the browser using HTML, CSS, and SVG.
Data visualization refers to representing data in graphical or pictorial forms, making even complex datasets easy to understand. Visualizations make it easier to spot patterns and conduct comparative analysis, which aids decision-making with minimal effort. Frameworks like D3.js excel in making these visual representations.
Background
D3.js was created by Mike Bostock, who previously worked on the Protovis toolkit, another data visualization tool. Although other frameworks exist for data visualization, D3.js has gained popularity for its flexibility and ease of learning. Instead of functioning as a monolithic framework, D3 solves the core problem by allowing efficient manipulation of data, reducing overhead, and offering flexibility.
Key Features of D3.js
D3.js stands out for several reasons that make it the preferred choice for data visualization:
Web Standards Integration:
D3 leverages modern web standards like HTML, CSS, and SVG, allowing the creation of powerful visualizations that work seamlessly in browsers.
Data-Driven Approach:
D3 enables users to pull data from different web nodes or servers, analyze it, and render visualizations based on the data. It also supports processing static datasets.
Versatile Graphics Creation:
D3 provides tools ranging from simple tables to advanced charts, like pie charts, bar graphs, and even complex GIS mapping. It supports customizable visualizations, making it adaptable to various needs.
Support for Large Datasets:
D3 efficiently handles large datasets and allows users to reuse predefined libraries, making the development process smoother and more efficient.
Transitions and Animations:
D3 simplifies the creation of animations and transitions, handling the logic implicitly. Developers don't need to manually manage transitions, and the library ensures responsive and smooth animation rendering.
DOM Manipulation:
One of D3's standout features is its ability to manipulate the Document Object Model (DOM) dynamically, making it highly flexible for managing the properties of its handlers.
Syntax:
D3 uses the JavaScript functions to carry out most of the selection, transition and data binding tasks. CSS also plays a key role in styling the components. Moreover, JavaScript functions can be scripted in such a way that they can read out data present in other formats.
Selection:
Before working on a dataset, the major task to be carried out is selection, i.e. retrieval of data from dataset. D3 enables the selection task by passing a predetermined tag as a parameter to the select function. Similarly, one can work up on various datasets defined under specific tags. Parameters to selectAll() can be tag, class, identifier or attribute. Elements can be modified or added or removed or manipulated and all this is based entirely on data.
d3.selectAll("pre") // It select all elements defined under the <pre> tag .style("color", "cyan"); // set style "color" to value "cyan" colorTransitions:
Transitions can make the values and attributes for a dataset dynamic. In above scenario, notice that for all the elements coming as a subset of pre tag, transitioned accordingly.
d3.selectAll("pre") // select all <pre> elements .transition("transitionEx") // Declaring transition named as "transitionEx" .delay(10) // transition starting after 10ms .duration(50); // transitioning during 50msFor more advanced usages, D3 makes the use of loaded data for creation of objects and manipulation, attributes addition and transitioning is done accordingly. All these operations come under the Data Binding part.
Setting up D3.js environment:
In order to make use of D3 for a website or webpage, first thing that needs to be taken care of is its installation or import of library into the webpage.
The D3 is an open source library. The source code is freely available on the D3.js website. Download the latest version of the library.(5.7.0 currently) 
Download D3 library from the source link[/caption]
Unzip the .zip file which obtained after the completion of download. Locate the d3.min.js file which is the minimal version of D3 source code. Copy that file and include it in the root folder or the main library directory of web page. In webpage, include the d3.min.js file as shown.
HTML <!DOCTYPE html> <html lang="en"> <head> <!--Adding the source file of D3 here --> <script src="../d3.min.js"></script> </head> <body> <script> // write your own d3 code here </script> </body> </html>
Note: D3 doesn't support Internet Explorer 8 or its lower versions. Preferably use Safari/ Mozilla Firefox or Chrome.
Example: The basic example shown below demonstrates the use of D3 for SVG object creation i.e. circle in scenario within in a HTML document.
HTML <!DOCTYPE html> <html> <meta charset="utf-8"> <body> <svg width="960" height="500"></svg> <div id="circle"></div> // Declaring the script type <script type="text/javascript"> // Creating a variable to store SVG attributes var myGraphic = d3.select("#circle") // applying the svg type attribute .append("svg") // initializing the width of the object pane .attr("width", 500) // initializing the height of the object pane .attr("height", 500); myGraphic.append("circle") // Outline color attribute set to blue .style("stroke", "blue") // Fill color attribute set to red .style("fill", "red") // Radius attribute set to 100 .attr("r", 100) // X-coordinate set to 300px .attr("cx", 300) // Y-coordinate set to 100px .attr("cy", 100) // applying action when the mouse pointer hovers over the circle .on("mouseover", function () { d3.select(this).style("fill", "lavender"); }) .on("mouseout", function () { d3.select(this).style("fill", "red"); }); </script> <script src="https://d3js.org/d3.v4.min.js"></script> </body> </html> Output:
Advantages:
- D3 supports web standards such as HTML, CSS, SVG which are known to all programmers, thus it can be used easily by anyone. In short, D3 exposes the capabilities of web standards such as HTML5, CSS3 and SVG.
- It is quite lightweight and flexible with the code which is reusable, thus preferable.
- It gives a wider control to the user to manage the visualization and data then the other API's or frameworks available.
- Being an open source framework, one can easily manipulate the source code of D3 as per his/her need.
Disadvantages:
- D3 is not compatible with older versions of browsers. In case, if someone wishes to visualize the data with backward compatibility, the visualization might necessarily be static, because of poor compatibility.
- Security is still a challenge for D3. Data can't easily be hidden or protected using D3.
Applications:
Its advantages is preferable in various data visualization fields. Some of the major domains wherein D3 is used is as follows:
- Basic charting and graph analytic visualizations.
- Network visualizations.
- Data dashboard development modules.
- Web Maps creation and synthesis.
- Interactive data representation.
Related Article: HTML | SVG-Basics