JavaScript supports eight data types: Number, BigInt, Boolean, String, Null, Undefined, Symbol, and Object. In this article, you’ll learn about all eight JavaScript data types and how to use them.
JavaScript Data Types
Data types in JavaScript can be broadly classified into two categories: Primitive data types and Non-primitive data types. An Object is a non-primitive or complex data type, and the rest are primitive data types.
JavaScript is a dynamically-typed language, meaning variable types are checked during run-time. The same variable can hold values of different types at any time.
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If you want to find the current data type of a variable, use the typeof operator.
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1. Number Data Type in JavaScript
The number data type in JavaScript uses the IEEE-754 format to represent both integer and floating-point numbers. You can perform many operations on numbers in JavaScript like addition, subtraction, division, multiplication, and so on. To perform more complex operations, you can use the built-in Math object.
Some examples to create numbers in JavaScript:
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Integer Numbers
The following statement creates a variable holding an integer:
If you want to create octal (base 8) literals, you need to use the 0o prefix with the sequence of octal digits (digits from 0 to 7).
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Similarly, if you want to create hexadecimal (base 16) literals, use the 0x prefix with the sequence of hexadecimal digits(0 to 9, and A to F).
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Floating-Point Numbers
The following statement creates a variable holding a floating-point number:
You can use e-notation to represent very large or very small numbers.
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JavaScript also provides other special numeric values that belong to the number data type—NaN, Infinity, and -Infinity.
NaN: NaN stands for Not a Number which means an invalid number. For example, if you divide a string and a number, the result will be NaN. console. log(“MakeUseOf”/10); Output: NaN Interestingly enough, NaN is not equal to anything, including itself. console. log(NaN == NaN);console. log(NaN == (“MakeUseOf”/10));console. log(NaN === NaN); Output: falsefalsefalse Also, if a mathematical expression somewhere contains NaN, the result is always NaN. Infinity and -Infinity: Infinity and -Infinity represents the mathematical ∞ and -∞ respectively.
2. BigInt Data Type in JavaScript
BigInt is a primitive data type in JavaScript that can represent integers with arbitrary precision. Since the number data type cannot represent values greater than (2⁵³-1) or values less than -(2⁵³-1), BigInt is used in such cases to represent very large or small numbers.
BigInt numbers are rarely used. But if you really need to represent big numbers, e.g. for cryptography, calculating the factorial of large numbers, representing the mass of the sun, microsecond-precision timestamps, and so on, BigInt is what you want to use.
You can create a BigInt value by appending n to the end of an integer or by using the constructor.
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The BigInt data type is a relatively recent addition to the language and is currently supported by almost all browsers except Internet Explorer.
3. Boolean Data Type in JavaScript
The boolean data type can have two values: true and false. Boolean values are the result of logical comparisons.
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You can convert a value of any other data type to a boolean data type using the Boolean() function.
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4. String Data Type in JavaScript
A string is a sequence of zero or more characters. Strings in JavaScript are immutable and are mainly used to represent textual data. The indexing of strings starts from 0 i.e., the first element is at index 0, the second at 1, and so on.
Strings must be surrounded by quotes. You can use any of the three types of quotes to create a string: Single quotes, Double quotes, or Backticks.
Single and Double quotes practically do the same thing, but a string that starts with a double quote must end with a double quote. The same rule applies to the single quote too.
Backticks are template literals and provide some extended functionality. You can embed variables, expressions, and even function calls within the string.
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JavaScript also provides several String methods to manipulate strings.
5. Null Data Type in JavaScript
The null data type has only one value: null. It represents the intentional absence of any object value.
Many programmers get confused between null and undefined. It’s tricky to understand the difference between null and undefined in JavaScript.
6. Undefined Data Type in JavaScript
The undefined type is a special type that means “value is not assigned”. When you declare a variable but do not initialize it, an undefined value is assigned to the variable.
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You can explicitly assign undefined to a variable, but it’s highly recommended to avoid it.
7. Symbol Data Type in JavaScript
A Symbol is a unique and immutable primitive value. It’s mainly used to create unique identifiers for objects.
You can create a symbol using the Symbol() function. It also accepts an optional description (name), but for debugging purposes only.
The Symbol() function creates a new unique value every time it is called, even if you create symbols with the same description, the values would be different.
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8. Object Data Type in JavaScript
In JavaScript, objects are collections of key-value pairs, where the key is a string and value can be any data type.
You can create an empty object in JavaScript using the “object constructor” syntax (new Object()) or the “object literal” syntax (curly braces {…}).
Each object contains an optional list of properties, where a property is a key:value pair. You can access the values from the object using dot-notation or array-like notation (square brackets).
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How Does JavaScript Work?
JavaScript is one of the most popular programming languages on the web today. You can use JavaScript to create websites, web applications, server applications, games, mobile apps, etc. Suffice to say, you can do almost anything you can think up with JavaScript.
But do you know how does JavaScript works under the hood?
