JavaScript Cheat Sheet That Will Make You A Better Developer

As you may know, JavaScript is a programming language that powers the dynamic behavior on most websites. Alongside HTML and CSS, it is a core technology that runs the web. In this article, I’ll give you a JavaScript cheat sheet that will help you in your JavaScript journey.

In this article you will find:

• JavaScript Array Functions
• JavaScript Boolean Methods
• JavaScript Arithmetic Operators
• JavaScript Global Functions
• JavaScript Loops
• JavaScript Logical Operators
• JavaScript Bitwise Operators
• JavaScript Functions
• JavaScript Escape Characters
• JavaScript String Methods
• JavaScript Pattern Modifiers
• Brackets
• Metacharacters

JavaScript Array Functions

• concat() -> Join several arrays into one
• copyWithin() ->Copy array elements within the array, to and from specified positions
• indexOf() -> Return the primitive value of the specified object
• includes() -> Check if an array contains the specified element
• join() -> Combine elements of an array into a single string and return the string
• entries() -> Return a key/value pair Array iteration Object
• every() ->Check if every element in an array with a static value
• fill() -> Fill the elements in an array with a static value
• filter() -> Create a new array with every element in an array that passes a test
• find() -> Return the value of the first element in an array that passes a test
• forEach() -> Call a function for each array element
• from() -> Create an array from an object
• lastIndexOF() -> Give the last position at which a given element appears in an array
• pop() -> Remove the last element of an array
• push() -> Add a new element at the end of an array
• reverse() -> Sort elements in descending order
• reduce() -> Reduce the values of an array to a single value (going left to right)
• reduceRight() -> Reduce the values of an array to a single value(going right to left)
• shift() -> Remove the first element of an array
• slice() -> Pull a copy of a portion of an array into a new array object
• sort() -> Sort elements alphabetically
• splice() -> Add elements in a specified way and position
• unshift() -> Add a new element to the beginning of an array

JavaScript Boolean Methods

• toString() -> Convert a Boolean value to a string and return the result
• valueOf() -> Return the first position at which a given element appears in an array
• toSource() -> Return a string representing the source code of the object

JavaScript Arithmetic Operators

• + -> Addition
• – -> Substraction
• * -> Multiplication
• / -> Division
• (…) -> Grouping operator (operations within brackets are executed earlier than those outside)
• % -> Modulus (remainder)
• ++ -> Increment numbers
• — -> Decrement numbers
• == -> Equal to
• === -> Equal value and equal type
• != -> Not Equal
• !== -> Not equal value or not equal type
• > -> Greater than
• < -> Lesser than
• >= -> Greater than or equal to
• <= -> Lesser than or equal to
• ? -> Ternary operator

JavaScript Global Functions

• decodeURI() -> Decode a Uniform Resource Identifier (URI) created by encode URI
• decodeURIComponent() -> Decode a URI component
• encodeURI() -> Encode a URI into UTF-8
• encodeURIComponent() -> Same but for URI components
• eval() -> Evaluate JavaScript code represented as a string
• inFinite() -> Determine whether a value is a finite number
• isNan() -> Determine whether a value is a number
• Number() -> Convert an object’s value to a number
• parseFloat() -> Parse a string and return a floating point number
• parseInt() -Parse a string and return an integer

JavaScript Loops

• for -> The most common way to create a loop in JavaScript
• while -> Set up conditions under which a loop executes
• do while -> Similar to the while loop but it executes at least once and performs a check at the end to see if the condition is met to execute again
• break -> Stop and exit the cycle if certain conditions are met
• continue -> Skip parts of the cycle if certain conditions are met

JavaScript Logical Operators

• && -> Logical AND
• || -> Logical OR
• ! -> Logical NOT

JavaScript Bitwise Operators

• & -> AND statement
• | -> OR statement
• ^ -> XOR
• ~ -> NOT
• << -> Left shift
• >> -> Right shift
• > -> Shift

JavaScript Functions

• alert() -> Output data in an alert box in the browser’s window
• confirm() -> Open up yes/no dialog and return true/false result
• console.log() -> Write information to the browser’s console
• document.write() -> Write directly to the HTML document
• prompt() -> Create a dialog for user input

JavaScript Escape Characters

• \’ -> Single quote
• \” -> Double quote
• \\ -> Bachslash
• \b -> Backspace
• \f -> Form feed
• \n -> New line
• \r -> Carriage return
• \t -> Horizontal tabulator
• \v -> Vertical tabulator

JavaScript String Methods

• charAt() -> Return character at a specified position inside a string
• charCodeAt() -> Give the Unicode of the character at that position
• concat() -> Concatenate two or more strings into one
• fromCharCode() -> Return a string created from the specified sequence of UTF-16 code units
• indexOf() -> Provide the position of the first occurrence of specified text within a string
• lastIndexOf() -> Same as indexOf() but returns last occurrence
• match() -> Retrieve the matches of a string against a search pattern
• replace() -> Find and replace specified text in a string
• search() -> Execute a search for a matching text and return its position
• slice() -> Extract a section of a string and return it as a new string
• split() -> Split a string object into an array of strings at a specified position
• startsWith() -> Check whether a string begins with specified characters
• substr() -> Similar to slice() but extracts a substring depended on a specified number of characters
• substring() -> Similar to slice() but can’t accept negative indices
• toLowerCase() -> Convert string to lowercase
• toUpperCase() -> Convert string to upper case
• valueOf() -> Return the primitive value of a string object

JavaScript Pattern Modifiers

• e -> Evaluate replacement
• i -> Perform case-insensitive matching
• g -> Perform global matching
• m -> Perform multiple line matching
• s -> Treat strings as a single line
• x -> Allow comments and whitespace in pattern
• U -> Ungreedy pattern

JavaScript Brackets

• [abc] -> Find any of the characters in the brackets
• [^abc] -> Find any character not in the brackets
• [0-9] -> Find the digit specified in the brackets
• [A-z] -> Find any character from uppercase A to lowercase z
• (a|b|c) -> Find any of the alternatives separated with |

JavaScript Metacharacters

• . -> Find a single character, except newline or line terminator
• \w -> Word character
• \W -> Non-word character
• \d -> A digit
• \D -> A non-digit character
• \s -> Whitespace character
• \S -> Non-whitespace character
• \b -> Find a match at the beginning/end of a word
• \B -> Find a match not at the beginning/end of a word
• \u0000 -> NUL character
• \n -> A new line character
• \f -> Form feed character
• \r -> Carriage return character
• \t -> Tab character
• \v -> Vertical tab character
• \xxx -> Character specified by an octal number xxx
• \xxd -> Latin character specified by a hexadecimal number dd
• \udddd -> Unicode character specified by a hexadecimal number dddd