computer science

Reactive user interface

Reactive user interface is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Reactive user interface rather than just read about it. In short: A human-to-computer user interface is said to be "reactive" if it has the following characteristics: The user is immediately aware of the effect of each "gesture". Gestures can be keystrokes, mouse clicks, menu selections, or more esoteric inputs.

Key takeaways

Reactive user interface belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Reactive user interface to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Reactive user interface from memory before moving on to harder problems.

Reference excerpt

A human-to-computer user interface is said to be "reactive" if it has the following characteristics:

The user is immediately aware of the effect of each "gesture". Gestures can be keystrokes, mouse clicks, menu selections, or more esoteric inputs. The user is always aware of the state of their data. Did I just save those changes? Did I just overwrite my backup by mistake? No data is hidden. In a figure-drawing program, the user can tell whether a line segment is composed of smaller segments. The user always knows how to get help. Help may be context-sensitive or modal, but it is substantial. A program with a built-in help browser is not reactive if its content is just a collection of screen shots or menu item labels with no real explanation of what they do. Reactivity was a major goal in the early user interface research at MIT and Xerox PARC. A computer program which was not reactive would not be considered user friendly no matter how elaborate its presentation. Early word-processing programs whose on-screen representations look nothing like their printer output could be reactive. The common example was WordStar on CP/M. On-screen, it looked like a markup language in a character cell display, but it had deep built-in help which was always available from an on-screen menu bar, and the effect of each keystroke was obvious.

References

Worked examples

Example 1 — a first encounter with Reactive user interface

Start with the simplest possible case. Write down what Reactive user interface claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Reactive user interface before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Reactive user interface ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Reactive user interface

In research: Reactive user interface appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Reactive user interface in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Reactive user interface is common in secondary-school and first-year university syllabi. It links to neighbouring topics Software engineering stubs, User interfaces, so understanding it makes those chapters shorter.
In everyday life: Look for Reactive user interface outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Reactive user interface in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Reactive user interface means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Reactive user interface out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Reactive user interface in simple terms?

A human-to-computer user interface is said to be "reactive" if it has the following characteristics: The user is immediately aware of the effect of each "gesture". Gestures can be keystrokes, mouse clicks, menu selections, or more esoteric inputs.

Why does Reactive user interface matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Reactive user interface?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Reactive user interface.