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JavaScript: Encoding

At machine level, the computer operates only with the numbers 0 and 1. This is called binary code, the ones and zeros are called bits, which is derived from the term "binary digit".

The numbers that we usually use in the decimal system are encoded using binary numbers:

  • 0 ← 0
  • 1 ← 1
  • 2 ← 10
  • 3 ← 11
  • 4 ← 100
  • 5 ← 101

But does it deal with text? The computer isn't aware of letters, punctuation, and other text characters. All these characters are encoded by numbers too.

We can take the English alphabet and give each letter a number, starting with one:

  • a ← 1
  • b ← 2
  • c ← 3
  • d ← 4
  • ...
  • z ← 26

Then you can teach the computer to understand this table and translate text into numbers and vice versa:

  • hello8 5 12 12 15
  • 7 15 15 4good

These tables that match letters and numbers are called encodings. Besides letters of the alphabet, encoding tables include punctuation marks and other useful characters. You've probably come across such encodings as ASCII or UTF-8.

Different encodings have different numbers of characters. At first, small tables like ASCII were enough for programmers. But they usually contain only Latin letters, a few simple characters like % and ?, and special control characters like newline (/n).

With the development of computers, different countries needed their own comprehensive tables. Including Cyrillic letters, hieroglyphs, Arabic script, additional mathematical and typographic characters, and even emojis as time went on.

One Unicode standarts standard in particular, utf-8, is the one used in most cases today. It includes characters from almost all of the written languages found in the world. Therefore, a letter written by someone from China in Chinese can easily be opened and read natively on a computer in Finland (whether the reader would understand it or not is another question).

Programmers have to deal with encodings regularly. Unicode support in different programming languages is carried out on a different level. Moreover, encodings must be declared when working with databases and files.

Instructions

In JavaScript you can "query" and print any ASCII character. For example:

console.log(String.fromCharCode(63));

Character 63 will be printed - a question mark. You can print any character this way.

Find an ASCII table on the internet. You can use queries like "ascii codes table" or "ascii codes". Generally, these tables give codes in several number systems: decimal, binary, octal and hexadecimal. We are interested in the decimal code (dec or decimal).

Using the example above and the table you found, print the characters ~, ^ and % (each on their own line).

(Of course, you could cheat and just do something like console.log('~'), but that would be no fun at all :)

The exercise doesn't pass checking. What to do? 😶

If you've reached a deadlock it's time to ask your question in the «Discussions». How ask a question correctly:

  • Be sure to attach the test output, without it it's almost impossible to figure out what went wrong, even if you show your code. It's complicated for developers to execute code in their heads, but having a mistake before their eyes most probably will be helpful.
In my environment the code works, but not here 🤨

Tests are designed so that they test the solution in different ways and against different data. Often the solution works with one kind of input data but doesn't work with others. Check the «Tests» tab to figure this out, you can find hints at the error output.

My code is different from the teacher's one 🤔

It's fine. 🙆 One task in programming can be solved in many different ways. If your code passed all tests, it complies with the task conditions.

In some rare cases, the solution may be adjusted to the tests, but this can be seen immediately.

I've read the lessons but nothing is clear 🙄

It's hard to make educational materials that will suit everyone. We do our best but there is always something to improve. If you see a material that is not clear to you, describe the problem in “Discussions”. It will be great if you'll write unclear points in the question form. Usually, we need a few days for corrections.

By the way, you can participate in courses improvement. There is a link below to the lessons course code which you can edit right in your browser.

Definitions

  • Encoding - is a set of characters encoded using numbers to represent text digitally.


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