In addition to properties, data has methods - functions within properties. Basically, it means that methods work and are called like functions, but do it like a property using a dot notation.
const name = 'Robb'; const upperName = name.toUpperCase(); console.log(upperName); // => 'ROBB'
Inline methods always apply to the data they are linked with. The
.toUpperCase() method returns the same string but converts all characters to uppercase. Data usually has many more methods than properties, for example, strings have several dozens of them. In the documentation they may seem to be described weirdly at first glance: String.prototype.toLowerCase(). This description reveals some internal implementation details which are not important right now, moreover, we haven't studied all the necessary basics to talk about prototypes.
Numbers have methods as well:
const temperature = 22.93; // Rounding to one decimal place const roundedTemperature = temperature.toFixed(1); // This method returns a string containing the rounded number console.log(roundedTemperature); // => '22.9' // They can be called directly like this // The brackets are necessary, or else it won't work (22.93).toFixed(1); // '22.9'
FYI. Technically, it's a bit more complicated. It's not the numbers themselves that have methods, but the data (objects) of the Number type. Numbers written in variables or constants are automatically converted to this type when called, this process is called boxing.
Why do we need methods? Why not just use functions? The situation with numbers is even more complicated. Some operations are implemented as methods of numbers, such as
.toFixed(), and most of them are implemented as methods accessible via
There are two reasons why it's done that way:
- Not all functions are linked to a specific value. For example,
Math.min(). This function finds the minimum of all numbers passed to it. It doesn't make sense to make this function a method of a particular number, like
(1).min(). It has no connection to any particular number
On the other hand, functions that work with a particular number should be implemented as methods for the sake of consistency. Such functions include calculating the modulus of a number. I.e., instead of
Math.abs(-10), it's more reasonable to have
Convert the string text to lowercase and print it.
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.