JavaScript Lessons for Beginners / #4 – Variables and Data Types in JS

In this lesson, we will learn to work with variables and understand different data types. You can find the homework code and useful information on the website mentioned in the description.

A variable is like a memory cell in a computer where you can store data such as numbers, strings, or boolean expressions. It allows you to reference and manipulate the stored data by performing various operations on it. In programming languages like JavaScript, variables are essential for storing different values.

Creating variables makes it easier to work with them. To create a variable, we use the keyword 'var', which is short for 'variable'. The name of the variable should be meaningful and not contain special symbols like $ or %. It's also important to end each line with a semicolon. When naming a variable, it should make logical sense and be easily understandable.

Setting the value is done inside a cell or a variable. We can set any value in a new line, for example by assigning numbers to it.

Working with Variables Variables can be used to store and manipulate data, such as performing mathematical operations. The value of a variable can be displayed on the screen using console.log. It's possible to concatenate strings and values by adding a plus sign between them.

Manipulating Variables Variables can be created, assigned values, and their values can be changed at any point in the program. This allows for flexibility in manipulating data without having to create new variables each time.

In programming, you can create variables using the keyword 'var' or constants using the keyword 'const'. The difference is that a constant cannot be redefined. When creating a constant, its value must be assigned immediately upon creation and cannot be changed later. You can also create as many variables or constants as needed within a program.

Data Types in JavaScript In JavaScript, you can set whole numbers and decimal numbers as variables. You can also store strings in single or double quotes. Additionally, you can store boolean expressions (true or false) inside variables. JavaScript does not have strict typing, meaning that a variable's data type is determined by its value.

Variable Declaration and Data Type Conversion When creating variables in JavaScript, their data types are defined by the assigned values. For example, if one variable holds a number and another holds a string, they will be of different data types. When adding a number to a string in JavaScript, the result will be treated as a concatenated string rather than an arithmetic sum due to automatic type conversion.

JavaScript allows for the combination of data types without errors.