D3.js interview questions

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

Below are the list of Top D3.js interview questions and answers for beginners.

1. What is D3.js?
2. What does D3 stand for?
3. Who developed D3.js?
4. Why to use  D3.js?
5. How D3.js identify on which elements to operate?
6. Explain selections in D3.js?
7. Explain, what is the use of “Enter” and “Exit” selection in D3.js?
8. List Type of sliders are available in D3.js?
9. Explain transition in D3.js?
10. List the command to interpolate two objects in D3.js?
11. which is the correct way to use XML file for d3?
12. What is the best way to create the stacked chart in d3 js?
13. How to import XML data using d3.js?
14. Which is not a valid scale in d3 js?
15. What is different between d3.scale.linear() and d3.scaleLinear().
16. How to alter zoom modes in d3 js?
17. How to set initial zoom level in D3.js?
18. How to resize an SVG when the window is resized in d3.js?
19. How to get Mouse position in D3.js?
20. What is the difference between canvas and SVG in d3.js?
21. How to format the date in d3.js?
22. List types of loops available in D3.js with syntax?
23. Explain axes in D3.js?How to create d3.js axes without numbering?
24. Explain Transition is D3.js?
25. How to calculate the area of the polygon in d3.js?

Q1. Define D3.js?

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.

Q2. What does D3 stand for?

D3 stands for Data-Driven Documents

Q3. 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.

Q4. 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.

Q5. 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");

Q6. Explain selections in D3.js ?

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

Q7. 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.

Q8. 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

Q9. 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");

Q10. List the command to interpolate two objects in D3.js?

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

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