The let and const keywords:
The let keyword is used to declare variables that are meant to be reassigned later on in the code. This is similar to the var keyword, which was previously used for the same purpose. The main difference between the two is that the scope of a let variable is limited to the block in which it is defined, whereas the scope of a var variable is the entire function in which it is defined.
On the other hand, the const keyword is used to declare variables that are meant to be read-only. Once you declare a variable with the const keyword, you cannot reassign it to a different value. This can be useful when you want to ensure that a certain value remains constant throughout your code.
Here’s an example of an arrow function:
As you can see, the arrow function consists of a set of parameters enclosed in parentheses, followed by the => operator and the function body.
The function body can be a single expression, in which case the return statement is implied. If the function body consists of multiple statements, you will need to use curly braces and include an explicit return statement.
Here’s an example of an arrow function with a function body:
Arrow functions are often used in combination with higher-order functions such as map, filter, and reduce. For example:
Here’s an example of a class:
As you can see, the class definition consists of a constructor function and a toString method. The constructor function is used to initialize the object, and the toString method is used to return a string representation of the object.
To create an instance of the classes, you use the new keyword followed by the class name and the arguments for the constructor function. In the example above, we create a new instance of the Point class with the x value set to 1 and the y value set to 2.
One of the advantages of using classes is that they provide a way to organize your code and encapsulate related properties and behaviors. This makes it easier to maintain and reuse your code.
Another advantage of classes is that they support inheritance, which allows you to create a new class that is based on an existing class. The new class can reuse the properties and behaviors of the existing class and add its own unique characteristics.
Here’s an example of inheritance:
As you can see, the ColorPoint class extends the Point class and adds a new color property. It also overrides the toString method to include the color in the string representation of the object.
One of the advantages of using modules is that they provide a way to manage dependencies between different parts of your code. This makes it easier to reuse your code and avoid conflicts.
Another advantage of modules is that they support exporting and importing, which allows you to share code between different files and modules.
Here’s an example of a module:
As you can see, the math.js file exports the sum and difference functions, which can then be imported and used in the main.js file.