- 01Setting Up (What You'll Need)
- 02Creating Variables
- 03Conditionals (if Statements)
- 04Loops (for Statements)
- 05Creating Functions
- 06Working with Arrays
- 07Working with Objects
- 08Loops (while Statements)
- 09Working with Strings
- 10Using Classes (Object-Oriented Programming)
- 11Error Handling (try...catch)
- 12Destructuring and the Spread Syntax
- 13Async Code (Promise / async & await)
- 14Advanced Array Methods (filter and reduce)
- 15The switch Statement
- 16The Ternary Operator
- 17Inheritance (Extending Classes)
- 18How to Write Comments
- 19Logical Operators (AND, OR, NOT)
- 20Constants (Making Read-Only Values with const)
- 21Splitting and Joining Strings (split and join)
- 22Null-Safe Syntax (?? and ?.)
- 23Searching Arrays and Collections (includes and find)
- 24Transforming Arrays with map
- 25Two-Dimensional Arrays (Table-Shaped Data)
- 26Building a Custom Error Class
- 27Default Arguments (Setting Initial Values for Parameters)
- 28Using Set (Collections)
- 29Verifying Correctness with assert (Your First Step Into Testing)
- 30Higher-Order Functions (Passing a Function as an Argument)
- 31Stacks and Queues (Basic Data Structures)
- 32The Basics of Type Conversion (Casting)
- 33Introduction to Regular Expressions (Pattern Matching)
- 34The Binary Search Algorithm
- 35Building a Caesar Cipher (a Letter-Shifting Cipher)
- 36Understanding How Bubble Sort Works
- 37Building and Displaying Dates (Basic Year/Month/Day Operations)
- 38Writing Several Unit Tests Together (Multiple Test Cases)
- 39Speeding Up Calculations with Memoization (Caching)
- 40Normalizing Strings (trim and Case Unification)
- 41The Difference Between Shallow Copy and Deep Copy
- 42The Basics of Enums (Enumerated Types)
- 43Flattening Arrays (flatten)
- 44Reversing a String and Checking for a Palindrome
- 45Pairing Up Two Arrays (a zip Operation)
- 46Rounding Numbers (floor, ceil, and round)
- 47Multi-Line Strings (Template Literals)
- 48Returning Multiple Values from a Function (Array Destructuring)
- 49Finding the GCD and LCM (the Euclidean Algorithm)
- 50Formatting Numbers (Digit Alignment and Decimal Precision)
- 51Cleanup Processing with try/catch/finally
- 52Writing Type-Agnostic, General-Purpose Functions
- 53The Basics of Map (an Object for Key-Value Pairs)
- 54Generating Random Numbers
- 55Bitwise Operations (AND, OR, XOR, and Shift Operations)
- 56Using static (Static Class Properties and Methods)
- 57Waiting a Fixed Amount of Time (setTimeout and await)
- 58Watch Out for Floating-Point Rounding Error
- 59Transforming and Flattening at Once with flatMap()
- 60FizzBuzz (the Classic Practice Problem)
- 61Checking Whether a Number Is Prime
- 62Set Operations with Set (Union, Intersection, and Difference)
- 63Converting Number Bases (Binary and Hexadecimal)
- 64Checking That Brackets Match (an Application of Stacks)
- 65Checking for an Anagram
- 66Checking Whether a Year Is a Leap Year
- 67Converting Temperature (Celsius ⇄ Fahrenheit)
- 68Finding the Prime Factorization
- 69[Applied] Build a Simple To-Do List Tool
Converting Number Bases (Binary and Hexadecimal)
In this lesson you'll learn how to convert numbers to binary and hexadecimal in JavaScript, so you can understand the basic idea behind base conversion. This is for people searching "JavaScript base conversion" or "JavaScript toString hexadecimal."
Number.toString(base) converts a number into a string in a specified base. Conversely, parseInt(string, base) converts a string in that base back into a base-10 number. A base is a number representing "what counts as one unit at each digit" — base 10 is 10, binary is 2, and hexadecimal is 16.
The sample code converts the number 42 into a binary string with .toString(2), and into a hexadecimal string with .toString(16). Conversely, parseInt("101010", 2) converts the binary string "101010" back into the base-10 number 42, letting you confirm the conversion was done correctly.
A common beginner stumbling block is forgetting to specify the second argument (the base) for parseInt(). Omitting the base causes it to be interpreted as base 10, so you must always specify the base to correctly convert a binary or hexadecimal string. Understanding this idea of base conversion also deepens your understanding of what's going on inside a computer.
Since binary is commonly used inside a computer, and hexadecimal for things like color codes, this idea of base conversion is generally useful basic knowledge across all of programming. A CSS color specification like #FF0000 is also written in hexadecimal, so this knowledge comes into play throughout web development.
💡 Anything passed to console.log() appears in the output below.