JavaScript Cheat Sheet. Functions That Will Make Your Development Easier

Posted by TotalDC

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 makes the web run.

JavaScript Arrays

  • 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 pass a test
  • find() -> Return the value of the first element in an array that pass 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 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 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 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

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 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

Logical Operators

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

Bitwise Operators

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

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 browsers console
  • document.write() -> Write directly to the HTML document
  • prompt() -> Create a dialog for user input

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 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 lower case
  • toUpperCase() -> Convert string to upper case
  • valueOf() -> Return the primitive value of a string object

Pattern Modifiers

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

Brackets

  • [abc] -> Find any of the characters in the brackets
  • [^abc] -> Find any character not in the brackets
  • [0-9] -> Find 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 |

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

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