![var a = "init"
Text (strings)
var b = 1 + 2 + 3
Operations
var c = true
True or false statements
const PI = 3.14
Constant numbers
var name = {firstName:"John", lastName:”Doe"}
Objects
Objects
var person = {
firstName:"John",
lastName:"Doe",
age:20,
nationality:"German"
};
Arrays
var fruit = ["Banana", "Apple", "Pear"];
Array Methods
concat()
Join several arrays into one
indexOf()
Returns the first position at which a given element appears in an array
join()
Combine elements of an array into a single string and return the string
lastIndexOf()
Gives the last position at which a given element appears in an array
WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 3](https://image.slidesharecdn.com/jsclassnotesforinstitute-240514033405-3a7701d2/85/js_class_notes_for_-institute-it-is-very-useful-for-your-study-pdf-4-320.jpg)
![Convert strings to lowercase
toUpperCase()
Convert strings to uppercase
valueOf()
Returns the primitive value (that has no properties or methods) of a string object
Regular Expressions
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 — Non Greedy pattern
Brackets
[abc] Find any of the characters between the brackets
[^abc] Find any character not in the brackets
[0-9] Used to find any digit from 0 to 9
[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 — A match not at the beginning/end of a word
0 — NUL character
n — A new line character
f — Form feed character
r — Carriage return character
t — Tab character
v — Vertical tab character
WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 9](https://image.slidesharecdn.com/jsclassnotesforinstitute-240514033405-3a7701d2/85/js_class_notes_for_-institute-it-is-very-useful-for-your-study-pdf-10-320.jpg)
js_class_notes_for_ institute it is very useful for your study.pdf
- 1. Beginner’s Essential Javascript Cheat Sheet The language of the web.
- 2. Table of Contents Javascript Basics 2 Variables 2 Arrays 3 Operators 4 Functions 5 Loops 7 If - Else Statements 7 Strings 7 Regular Expressions 9 Numbers and Math 10 Dealing with Dates 12 DOM Node 14 Working with the Browser 18 Events 21 Errors 27 WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 1
- 3. Javascript Basics Including JavaScript in an HTML Page <script type="text/javascript"> //JS code goes here </script> Call an External JavaScript File <script src="myscript.js"></script><code></code> Including Comments // Single line comments /* comment here */ Multi-line comments Variables var, const, let var The most common variable. Can be reassigned but only accessed within a function. Variables defined with var move to the top when code is executed. const Cannot be reassigned and not accessible before they appear within the code. let Similar to const, however, let variable can be reassigned but not re-declared. Data Types var age = 23 Numbers var x Variables WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 2
- 4. var a = "init" Text (strings) var b = 1 + 2 + 3 Operations var c = true True or false statements const PI = 3.14 Constant numbers var name = {firstName:"John", lastName:”Doe"} Objects Objects var person = { firstName:"John", lastName:"Doe", age:20, nationality:"German" }; Arrays var fruit = ["Banana", "Apple", "Pear"]; Array Methods concat() Join several arrays into one indexOf() Returns the first position at which a given element appears in an array join() Combine elements of an array into a single string and return the string lastIndexOf() Gives the last position at which a given element appears in an array WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 3
- 5. pop() Removes the last element of an array push() Add a new element at the end reverse() Reverse the order of the elements in an array shift() Remove the first element of an array slice() Pulls a copy of a portion of an array into a new array of 4 24 sort() Sorts elements alphabetically splice() Adds elements in a specified way and position toString() Converts elements to strings unshift() Adds a new element to the beginning valueOf() Returns the primitive value of the specified object Operators Basic Operators + Addition - Subtraction * Multiplication / Division (..) Grouping operator % Modulus (remainder) ++ Increment numbers -- Decrement numbers WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 4
- 6. Comparison Operators == Equal to === Equal value and equal type != Not equal !== Not equal value or not equal type > Greater than < Less than >= Greater than or equal to <= Less than or equal to ? Ternary operator Logical Operators && Logical and || Logical or ! Logical not Bitwise Operators & AND statement | OR statement ~ NOT ^ XOR << Left shift >> Right shift >>> Zero fill right shift Functions function name(parameter1, parameter2, parameter3) { // what the function does } Outputting Data alert() Output data in an alert box in the browser window confirm() Opens up a yes/no dialog and returns true/false depending on user click console.log() Writes information to the browser console, good for debugging purposes WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 5
- 7. document.write() Write directly to the HTML document prompt() Creates an dialogue for user input Global Functions decodeURI() Decodes a Uniform Resource Identifier (URI) created by encodeURI or similar decodeURIComponent() Decodes a URI component encodeURI() Encodes a URI into UTF-8 encodeURIComponent() Same but for URI components eval() Evaluates JavaScript code represented as a string isFinite() Determines whether a passed value is a finite number isNaN() Determines whether a value is NaN or not Number() Returns a number converted from its argument parseFloat() Parses an argument and returns a floating point number parseInt() Parses its argument and returns an integer WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 6
- 8. Loops for (before loop; condition for loop; execute after loop) { // what to do during the loop } for The most common way to create a loop in Javascript while Sets up conditions under which a loop executes do while Similar to the while loop, however, it executes at least once and performs a check at the end to see if the condition is met to execute again break Used to stop and exit the cycle at certain conditions continue Skip parts of the cycle if certain conditions are met of 7 24 If - Else Statements if (condition) { // what to do if condition is met } else { // what to do if condition is not met } Strings var person = "John Doe"; Escape Characters ' — Single quote " — Double quote — Backslash b — Backspace f — Form feed n — New line r — Carriage return t — Horizontal tabulator WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 7
- 9. v — Vertical tabulator String Methods charAt() Returns a character at a specified position inside a string charCodeAt() Gives you the unicode of character at that position concat() Concatenates (joins) two or more strings into one fromCharCode() Returns a string created from the specified sequence of UTF-16 code units indexOf() Provides the position of the first occurrence of a specified text within a string lastIndexOf() Same as indexOf() but with the last occurrence, searching backwards match() Retrieves the matches of a string against a search pattern replace() Find and replace specific text in a string search() Executes a search for a matching text and returns its position slice() Extracts a section of a string and returns it as a new string split() Splits a string object into an array of strings at a specified position substr() Similar to slice() but extracts a substring depended on a specified number of characters substring() Also similar to slice() but can’t accept negative indices toLowerCase() WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 8
- 10. Convert strings to lowercase toUpperCase() Convert strings to uppercase valueOf() Returns the primitive value (that has no properties or methods) of a string object Regular Expressions 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 — Non Greedy pattern Brackets [abc] Find any of the characters between the brackets [^abc] Find any character not in the brackets [0-9] Used to find any digit from 0 to 9 [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 — A match not at the beginning/end of a word 0 — NUL character n — A new line character f — Form feed character r — Carriage return character t — Tab character v — Vertical tab character WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 9
- 11. xxx — The character specified by an octal number xxx xdd — Character specified by a hexadecimal number dd uxxxx — The Unicode character specified by a hexadecimal number xxxx Quantifiers n+ — Matches any string that contains at least one n n* — Any string that contains zero or more occurrences of n n? — A string that contains zero or one occurrences of n n{X} — String that contains a sequence of X n’s n{X,Y} — Strings that contains a sequence of X to Y n’s n{X,} — Matches any string that contains a sequence of at least X n’s n$ — Any string with n at the end of it ^n — String with n at the beginning of it ?=n — Any string that is followed by a specific string n ?!n — String that is not followed by a specific string n Numbers and Math Number Properties MAX_VALUE The maximum numeric value representable in JavaScript MIN_VALUE Smallest positive numeric value representable in JavaScript NaN The “Not-a-Number” value NEGATIVE_INFINITY The negative Infinity value POSITIVE_INFINITY Positive Infinity value Number Methods toExponential() Returns a string with a rounded number written as exponential notation toFixed() Returns the string of a number with a specified number of decimals WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 10
- 12. toPrecision() String of a number written with a specified length toString() Returns a number as a string valueOf() Returns a number as a number Math Properties E Euler’s number LN2 The natural logarithm of 2 LN10 Natural logarithm of 10 LOG2E Base 2 logarithm of E LOG10E Base 10 logarithm of E PI The number PI SQRT1_2 Square root of 1/2 SQRT2 The square root of 2 Math Methods abs(x) Returns the absolute (positive) value of x acos(x) The arccosine of x, in radians asin(x) Arcsine of x, in radians atan(x) The arctangent of x as a numeric value atan2(y,x) Arctangent of the quotient of its arguments ceil(x) Value of x rounded up to its nearest integer cos(x) The cosine of x (x is in radians) WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 11
- 13. exp(x) Value of Ex floor(x) The value of x rounded down to its nearest integer log(x) The natural logarithm (base E) of x max(x,y,z,...,n) Returns the number with the highest value min(x,y,z,...,n) Same for the number with the lowest value pow(x,y) X to the power of y random() Returns a random number between 0 and 1 round(x) The value of x rounded to its nearest integer sin(x) The sine of x (x is in radians) sqrt(x) Square root of x tan(x) The tangent of an angle Dealing with Dates Setting Dates Date() Creates a new date object with the current date and time WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 12
- 14. Date(2017, 5, 21, 3, 23, 10, 0) Create a custom date object. The numbers represent year, month, day, hour, minutes, seconds, milliseconds. You can omit anything you want except for year and month. Date("2017-06-23") Date declaration as a string Pulling Date and Time Values getDate() Get the day of the month as a number (1-31) getDay() The weekday as a number (0-6) getFullYear() Year as a four digit number (yyyy) getHours() Get the hour (0-23) getMilliseconds() The millisecond (0-999) getMinutes() Get the minute (0-59) getMonth() Month as a number (0-11) getSeconds() Get the second (0-59) getTime() Get the milliseconds since January 1, 1970 getUTCDate() The day (date) of the month in the specified date according to universal time (also available for day, month, fullyear, hours, minutes etc.) parse Parses a string representation of a date, and returns the number of milliseconds since January 1, 1970 WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 13
- 15. Set Part of a Date setDate() Set the day as a number (1-31) setFullYear() Sets the year (optionally month and day) setHours() Set the hour (0-23) setMilliseconds() Set milliseconds (0-999) setMinutes() Sets the minutes (0-59) setMonth() Set the month (0-11) setSeconds() Sets the seconds (0-59) setTime() Set the time (milliseconds since January 1, 1970) setUTCDate() Sets the day of the month for a specified date according to universal time (also available for day, month, fullyear, hours, minutes etc.) DOM Node Node Properties attributes Returns a live collection of all attributes registered to and element baseURI Provides the absolute base URL of an HTML element childNodes Gives a collection of an element’s child nodes WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 14
- 16. firstChild Returns the first child node of an element lastChild The last child node of an element nextSibling Gives you the next node at the same node tree level nodeName Returns the name of a node nodeType Returns the type of a node nodeValue Sets or returns the value of a node ownerDocument The top-level document object for this node parentNode Returns the parent node of an element previousSibling Returns the node immediately preceding the current one textContent Sets or returns the textual content of a node and its descendants Node Methods appendChild() Adds a new child node to an element as the last child node cloneNode() Clones an HTML element compareDocumentPosition() Compares the document position of two elements getFeature() Returns an object which implements the APIs of a specified feature WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 15
- 17. hasAttributes() Returns true if an element has any attributes, otherwise false hasChildNodes() Returns true if an element has any child nodes, otherwise false insertBefore() Inserts a new child node before a specified, existing child node isDefaultNamespace() Returns true if a specified namespaceURI is the default, otherwise false isEqualNode() Checks if two elements are equal isSameNode() Checks if two elements are the same node isSupported() Returns true if a specified feature is supported on the element lookupNamespaceURI() Returns the namespaceURI associated with a given node lookupPrefix() Returns a DOMString containing the prefix for a given namespaceURI, if present normalize() Joins adjacent text nodes and removes empty text nodes in an element removeChild() Removes a child node from an element replaceChild() Replaces a child node in an element Element Methods getAttribute() Returns the specified attribute value of an element node getAttributeNS() Returns string value of the attribute with the specified namespace and name WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 16
- 18. getAttributeNode() Gets the specified attribute node getAttributeNodeNS() Returns the attribute node for the attribute with the given namespace and name getElementsByTagName() Provides a collection of all child elements with the specified tag name getElementsByTagNameNS() Returns a live HTMLCollection of elements with a certain tag name belonging to the given namespace hasAttribute() Returns true if an element has any attributes, otherwise false hasAttributeNS() Provides a true/false value indicating whether the current element in a given namespace has the specified attribute removeAttribute() Removes a specified attribute from an element removeAttributeNS() Removes the specified attribute from an element within a certain namespace removeAttributeNode() Takes away a specified attribute node and returns the removed node setAttribute() Sets or changes the specified attribute to a specified value setAttributeNS() Adds a new attribute or changes the value of an attribute with the given namespace and name setAttributeNode() Sets or changes the specified attribute node setAttributeNodeNS() Adds a new namespaced attribute node to an element WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 17
- 19. Working with the Browser Window Properties closed Checks whether a window has been closed or not and returns true or false defaultStatus Sets or returns the default text in the statusbar of a window document Returns the document object for the window frames Returns all <iframe> elements in the current window history Provides the History object for the window innerHeight The inner height of a window’s content area innerWidth The inner width of the content area length Find out the number of <iframe> elements in the window location Returns the location object for the window name Sets or returns the name of a window navigator Returns the Navigator object for the window opener Returns a reference to the window that created the window outerHeight The outer height of a window, including toolbars/ scrollbars WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 18
- 20. outerWidth The outer width of a window, including toolbars/ scrollbars pageXOffset Number of pixels the current document has been scrolled horizontally pageYOffset Number of pixels the document has been scrolled vertically parent The parent window of the current window screen Returns the Screen object for the window screenLeft The horizontal coordinate of the window (relative to screen) screenTop The vertical coordinate of the window screenX Same as screenLeft but needed for some browsers screenY Same as screenTop but needed for some browsers self Returns the current window status Sets or returns the text in the statusbar of a window top Returns the topmost browser window Window Methods alert() Displays an alert box with a message and an OK button blur() Removes focus from the current window WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 19
- 21. clearInterval() Clears a timer set with setInterval() clearTimeout() Clears a timer set with setTimeout() close() Closes the current window confirm() Displays a dialogue box with a message and an OK and Cancel button focus() Sets focus to the current window moveBy() Moves a window relative to its current position moveTo() Moves a window to a specified position open() Opens a new browser window print() Prints the content of the current window prompt() Displays a dialogue box that prompts the visitor for input resizeBy() Resizes the window by the specified number of pixels resizeTo() Resizes the window to a specified width and height scrollBy() Scrolls the document by a specified number of pixels scrollTo() Scrolls the document to specific coordinates WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 20
- 22. setInterval() Calls a function or evaluates an expression at specified intervals setTimeout() Calls a function or evaluates an expression after a specified interval stop() Stops the window from loading Screen Properties availHeight Returns the height of the screen (excluding the Windows Taskbar) availWidth Returns the width of the screen (excluding the Windows Taskbar) colorDepth Returns the bit depth of the color palette for displaying images height The total height of the screen pixelDepth The color resolution of the screen in bits per pixel width The total width of the screen Events Mouse onclick The event occurs when the user clicks on an element oncontextmenu User right-clicks on an element to open a context menu ondblclick The user double-clicks on an element WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 21
- 23. onmousedown User presses a mouse button over an element onmouseenter The pointer moves onto an element onmouseleave Pointer moves out of an element onmousemove The pointer is moving while it is over an element onmouseover When the pointer is moved onto an element or one of its children onmouseout User moves the mouse pointer out of an element or one of its children onmouseup The user releases a mouse button while over an element Keyboard onkeydown When the user is pressing a key down onkeypress The moment the user starts pressing a key onkeyup The user releases a key Frame onabort The loading of a media is aborted onbeforeunload Event occurs before the document is about to be unloaded onerror An error occurs while loading an external file WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 22
- 24. onhashchange There have been changes to the anchor part of a URL onload When an object has loaded onpagehide The user navigates away from a webpage onpageshow When the user navigates to a webpage onresize The document view is resized onscroll An element’s scrollbar is being scrolled onunload Event occurs when a page has unloaded Form onblur When an element loses focus onchange The content of a form element changes (for <input>, <select>and <textarea>) onfocus An element gets focus onfocusin When an element is about to get focus onfocusout The element is about to lose focus oninput User input on an element oninvalid An element is invalid WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 23
- 25. onreset A form is reset onsearch The user writes something in a search field (for <input="search">) onselect The user selects some text (for <input> and <textarea>) onsubmit A form is submitted Drag ondrag An element is dragged ondragend The user has finished dragging the element ondragenter The dragged element enters a drop target ondragleave A dragged element leaves the drop target ondragover The dragged element is on top of the drop target ondragstart User starts to drag an element ondrop Dragged element is dropped on the drop target Clipboard oncopy User copies the content of an element oncut The user cuts an element’s content WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 24
- 26. onpaste A user pastes content in an element Media onabort Media loading is aborted oncanplay The browser can start playing media (e.g. a file has buffered enough) oncanplaythrough When browser can play through media without stopping ondurationchange The duration of the media changes onended The media has reached its end onerror Happens when an error occurs while loading an external file onloadeddata Media data is loaded onloadedmetadata Meta Metadata (like dimensions and duration) are loaded onloadstart Browser starts looking for specified media onpause Media is paused either by the user or automatically onplay The media has been started or is no longer paused onplaying Media is playing after having been paused or stopped for buffering onprogress Browser is in the process of downloading the media WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 25
- 27. onratechange The playing speed of the media changes onseeked User is finished moving/skipping to a new position in the media onseeking The user starts moving/skipping onstalled The browser is trying to load the media but it is not available onsuspend Browser is intentionally not loading media ontimeupdate The playing position has changed (e.g. because of fast forward) onvolumechange Media volume has changed (including mute) onwaiting Media paused but expected to resume (for example, buffering) Animation animationend A CSS animation is complete animationiteration CSS animation is repeated animationstart CSS animation has started Other transitionend Fired when a CSS transition has completed onmessage A message is received through the event source WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 26
- 28. onoffline Browser starts to work offline ononline The browser starts to work online onpopstate When the window’s history changes onshow A <menu> element is shown as a context menu onstorage A Web Storage area is updated ontoggle The user opens or closes the <details> element onwheel Mouse wheel rolls up or down over an element ontouchcancel Screen touch is interrupted ontouchend User finger is removed from a touch screen ontouchmove A finger is dragged across the screen ontouchstart Finger is placed on touch screen Errors try Lets you define a block of code to test for errors catch Set up a block of code to execute in case of an error WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 27
- 29. throw Create custom error messages instead of the standard JavaScript errors finally Lets you execute code, after try and catch, regardless of the result Error Name Values name Sets or returns the error name message Sets or returns an error message in string from EvalError An error has occurred in the eval() function RangeError A number is “out of range” ReferenceError An illegal reference has occurred SyntaxError A syntax error has occurred TypeError A type error has occurred URIError An encodeURI() error has occurred WebsiteSetup.org - Beginner’s Javascript Cheat Sheet 28