JavaScript: Getting characters from a string
Sometimes you have to get a single character from a string. For example, if the website knows the user's first name and surname, and at some point, you need to output it as J. Smith, you need to take the initial letter from the first name.
const firstName = 'Tirion';
console.log(firstName[0]); // => 'T'
A number encased in square brackets is the special syntax used for extracting a character from a string. The number is called the index, which represents the position of the character in the string. Indexes start with 0 in almost all programming languages – so to get the first character, you must set the index to 0. The index of the last element is equal to the length of the string minus one:
// String length is 6, so the last index is 5
const firstName = 'Tirion';
console.log(firstName[5]); // => 'n'
// Self-check. What will this code print?
const magic = '\nyou'
console.log(magic[1]); // => ?
You can use variables as well as numbers as an index. Here is an example with the same result (printing T), where the index in square brackets is a constant, not a number:
const firstName = 'Tirion';
const index = 0;
console.log(firstName[index]); // => 'T'
Technically, you can set the index beyond the word length. In our example, these are numbers from 6 and greater. JavaScript does not consider this behavior an error. Addressing a non-existent index will return undefined.
const firstName = 'Tirion';
console.log(firstName[10]); // => undefined
Instructions
Print the last character of the string constant name.
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.
Your exercise will be checked with these tests:
1import { expectOutput } from 'hexlet-basics/tests';
2
3const expected = 's';
4expectOutput(expected);
5Teacher's solution will be available in:
