There are numerous digital calculators available online. From simple fraction calculator to advanced scientific calculators, you can find the entire gamut of calculating tools on the Web. Ever wondered how they work? What exactly goes on behind the scenes, and how, in the name of science & mathematics, are they so accurate?  

This article pulls back the layers of digital abstraction and offers a quick glimpse behind the scenes. Let's start.

How Does An Online Calculator Work?

HTML and CSS form the outer layers of any online calculator, while JavaScript does all the heavy lifting. The Hyper Text Markup Language and Cascading Style Sheets look after the structure and style of a web calculator. JavaScript gives life to the tool and carries out all the dynamic & interactive operations, that is, the mathematical calculations, storing, and displaying of answers.

Now, any calculator comprises two primary elements, namely, the keys and the display. Cascading Style Sheet grids can be used to design the keys, as the buttons in online calculators are generally arranged in a grid-like format.
HTML defines the names and overall structure of an online calculator. is used to determine clickable buttons. word alphabetizer attributes describe the purposes of the controls that initiate math operations.
You must be thorough with concepts in Dynamic Object Model in HTML, object-oriented programming, iterations & conditions using FOR and IF/ELSE statements, etc., different in-built Java Script functions, Boolean operators, and event listeners & event delegation.  
addEventListener() is a JavaScript HTML DOM method that assigns event-listening capabilities to a particular element.

Event listening enables the calculator to listen for any key presses and determine which key was pressed exactly.

Data action attributes allow the JS interpreter to understand which key was clicked or pressed. Generic calculator designs assign data attributes only to math operator keys. paper checker online If a key has been pressed with no associated data action attributed to it, then it must be a number key.
When it comes to displaying numbers on the calculator screen one after another, we need to consider two things—the currently displayed number and the number of the key clicked. The textContent property of the clicked button and the .calculator__displayprovide those values.

This is where IF conditional statements come into the picture.  

If the display shows 0 and some key was clicked, then the textContent attribute will equal the key content of the key pressed.

And, if the display showed something else, then the new number must be appended with the one being displayed. String concatenation or connection is used to link the new key content with the displayed using the + sign and then assign it to textContent for displaying.

Well, that’s all the space we have for today. Hope this write-up was able to offer a clear & intuitive glimpse of how online calculators work behind the scenes. Wish to design your own online scientific or dissertation expert? Then boost your basics and start coding today.

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