D3.js Interview Questions & Answers

D3.js Interview Questions

Getting prepared for D3.js job? Do not panic, we will guide you how and what to answer in your interview. If you are preparing for D3.js job interview then go through Wisdomjobs interview questions and answers page. D3.js is a JavaScript library. Mostly used in producing interactive and dynamic data visualizations in web browsers. It is used in several number of websites. Some popular uses include creating interactive graphics for online news websites, information dashboards for viewing data, and producing maps. Many candidates are in need of this position. There are many openings for this job as this is much popular and used in all websites. Please have a look at D3.js interview questions and answers page to win your interview.

D3.js Interview Questions And Answers

D3.js Interview Questions
    1. Question 1. How To Data Binding Work In D3.js?

      Answer :

      The D3.js is data driven and the data () function is used to join the specified array object of data to the selected DOM elements and return updated selection.

      The data binding methods –

      1. data() function – This function Joins the data to the selected elements
      2. enter() function- This functions is used to creates a selection with placeholder references for missing elements
      3. exit() function – This functions is used to removes nodes and adds them to the exit selection which can be later removed from the DOM
      4. datum() function – This functions is used to injects data to the selected element without computing a join

      The Example looks like –

      var data Array = ["Hello,  This is data array!"];

      var select Data = d3.select("body").selectAll("p").data(dataArray)

            .text(function (dt) {   

          return dt;


    2. Question 2. What About The Selections In D3.js?

      Answer :

      The D3.Js helps us to select the elements and it allows us to select one or more elements in a HTML pages. It allows us to modify, append or remove elements based on CSS selectors.

      The selector methods-

      1. select() – It is used to selects the HTML element based on CSS Selectors.
      2. select All() -  It is used to select multiple elements from HTML DOM.
      3. append()
      4. html()
      5. text()
      6. attr()
      7. style() and
      8. classed()

    3. Question 3. What Are The Key Features Of D3.js?

      Answer :

      1. Data Driven
      2. DOM Manipulation
      3. Interaction and animation
      4. Custom Visualizations - Pie chart, graphs, bar charts or geospatial maps
      5. Transitions

    4. Question 4. List The Command To Interpolate Two Objects In D3.js?

      Answer :

      d3.interpolateObject(a,b) command is used to interpolate two objects in d3.js

    5. Question 5. Explain Transition In D3.js?

      Answer :

      A transition is a selection-like interface for animating changes to the DOM. Instead of applying changes instantaneously, transitions smoothly interpolate the DOM from its current state to the desired target state over a given duration.

      To apply a transition, select elements, call selection.transition and then make the desired changes.

      For example:



          .style("background-color", "red");

    6. Question 6. List Type Of Sliders Are Available In D3.js?

      Answer :

      There are 7 types of slider are available in D3.js,

      they are

      1. Default slider
      2. Slider with start value
      3. Slider with slide event: 0
      4. Slider with default axis
      5. Slider with custom axis
      6. Slider with min, max and step values
      7. Vertical slider

    7. Question 7. Explain Selections In D3.js?

      Answer :

      D3 implements a declarative approach, operating on arbitrary sets of nodes called selections.

    8. Question 8. How D3.js Identify On Which Elements To Operate?

      Answer :

      D3.js uses CSS-style selectors to identify elements on which to operate.


      d3.selectAll("p").style("color", "white");

    9. Question 9. Why Use To D3.js?

      Answer :

      You can use D3 js because:

      • D3.js lets you to build the data visualization framework
      • D3.js focuses on binding data to DOM elements.
      • D3.js is written in JavaScript and uses a functional style which means you can reuse code and add specific functions to your heart’s content.

    10. Question 10. Who Developed D3.js?

      Answer :

      Mike Bostock wrote D3.js based on his work during his Ph.D. studies at the Stanford Visualization Group. Mike worked at the The New York Times for a while and is now independently working on D3.js.

    11. Question 11. What Does D3 Stand For?

      Answer :

      D3 stands for Data-Driven Documents

    12. Question 12. Define D3.js?

      Answer :

      D3.js is defined as a JavaScript-based library for manipulating documents based on data. D3 helps you bring data to life using HTML, SVG, and CSS. D3’s emphasis on web standards gives you the full capabilities of modern browsers without tying yourself to a proprietary framework, combining powerful visualization components and a data-driven approach to DOM manipulation.

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