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D3.js interview questions

Top D3.js interview questions and answers for freshers and experienced

1. What is D3.js?

D3.js is a JavaScript 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.

2. What does D3 stand for?

D3 stands for Data-Driven Documents

3. Who developed D3.js?

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.

4. Why use to D3.js?

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.

5. How D3.js identify on which elements to operate?

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

Example:

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

6. Explain selections in D3.js ?

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

7. Explain, what is the use of “Enter” and “Exit” selection in D3.js?

In D3.js “Enter” selection is used to create new nodes for incoming data and “Exit” selection is used eliminate outgoing nodes that are no longer required.

8. List Type of sliders are available in D3.js?

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

  • Default slider
  • Slider with start value
  • Slider with slide event: 0
  • Slider with default axis
  • Slider with custom axis
  • Slider with min, max and step values
  • Vertical slider

9. Explain transition in D3.js?

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:

d3.select("body")
  .transition()
    .style("background-color", "red");

10. List the command to interpolate two objects in D3.js?

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