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The 8 Types of Data in JavaScript

Before we can discuss the different types of data in JavaScript, it’s crucial to understand what exactly data is in these computer programs. A data type is responsible for sending messages to the compiler or programmer on how the program intends to use the data. Data can be numeric, alphanumeric, or decimal and can be featured in other forms. Any type of data can be implemented in variables when installing JavaScript. Let’s discuss the eight different types of data in JavaScript to learn more about their operations within an application. 


The number type of data represents both integer and floating-point numbers. An integer could be n=123 and a floating-point number could be n=12.345. There are many operations for these numbers to be generated, including the most common—addition, subtraction, multiplication, and division. Besides integers and decimal-based numbers, JavaScript is also enabled to read “special numeric values†which belongs to a more specific data type, Infinity, and NaN. 


BigInt is a built-in data type that provides an efficient way to represent whole numbers larger than 253-1, which is the largest number that JavaScript can successfully represent with the number primitive. BigInt is predominantly used for documenting and interpreting arbitrarily large numbers. With this being said, BigInt numbers are rarely needed. This data type is currently available and supported in Firefox, Chrome, and Edge. 


This data type is a sequence composed of string or of connected characters that often make up words. Although, string-type data is equipped to create a string with any type of character or syntax, there are some characters that are exceptional. If you need to include a double quote, a tab, or a carriage return in a string, JavaScript has “escape codes†to allow you to implement those. For double and single quotes, these are “simple†quotes, which is what you see more often in string data. 

Boolean (Logical type)

The Boolean data type is broken up only into two values: true and false. This is intended to store “yes†and “no†values by using “true†for “yes†and “false†for “noâ€, making it easier for the computer application to read commands. Boolean values can also respond to numerical values and equations, such as 4 > 1, which would be false. “On†and “off†can also be interpreted for “true†and “false†for special commands. 

The “Null†Value

The “null†data type does not belong or correlate with any other data type in JavaScript. Null does not refer to any other value or a non-existing object. Simply put, it a special value that represents “nothingâ€, “emptyâ€, “or value unknownâ€. For example, the command “let age = null†would determine the age as an “unknown†value. 

The “Undefined†Value 

Much like the “null†value, the “undefined†value makes its own category. Undefined in JavaScript refers to “value is not assignedâ€. If a variable is declared, but not assigned, then its value is undefined. For example:

Let age;

Alert(age); // shows “undefinedâ€

“Undefined†results out the fact that the age was not assigned a numerical value nor a “null†value. “Undefined†is predominantly used for a default value when things are unassigned. 

Objects and Symbols

Objects and symbols are the most recent primitive type introduced in JavaScript. This type of data is considered a counterpart to types such as Number, Strong, and Boolean. Symbols can be created using “(“ and “)â€. This, in turn, creates unique identifiers whenever objects need to be interpreted. Objects are used to store collections of data and other complex entities if need be. 


The Typeof operator in JavaScript coincides with String data type. It returns a string indicating the type of the unevaluated operand, which is an expression representing the object or primitive whose type is to be returned. The typeof operator is what allows an application to determine a data type, including all of the types we have discussed. For any other type that was not pre-installed, it will identify the data as “objectâ€. 

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