If you want to build dynamic webpages, you’ll have to supplement your HTML and CSS knowledge with an understanding of JavaScript. This scripting language is considered an essential in modern web development.
You can build all kinds of interesting interactive apps and websites with JavaScript, but there’s much to learn on the way. With that in mind, we have created the following JavaScript cheat sheet for you.
The cheat sheet can serve as a quick refresher on JavaScript elements any time you need one. It’s handy for newbies and experts alike.
FREE DOWNLOAD: This cheat sheet is available as a downloadable PDF from our distribution partner, TradePub. You will have to complete a short form to access it for the first time only. Download The Ultimate JavaScript Cheat Sheet.
The Ultimate JavaScript Cheat Sheet
| Shortcut | Action |
|---|---|
| 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 passes a test |
| 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 |
| 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 |
| 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 |
| - | Subtraction |
| * | 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 |
| 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 | |
| alert() | Output data in an alert box in the browser window |
| confirm() | Open up a yes/no dialog and return true/false depending on user click |
| console.log() | Write information to the browser console (good for debugging purposes) |
| document.write() | Write directly to the HTML document |
| prompt() | Create a dialog for user input |
| Global Functions | |
| decodeURI() | Decode a Uniform Resource Identifier (URI) created by encodeURI or similar |
| 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 |
| isFinite() | Determine whether a passed value is a finite number |
| isNaN() | Determine whether a value is an illegal 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, however, 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 mets |
| continue | Skip parts of the cycle if certain conditions are met |
| Escape Characters | |
| \' | Single quote |
| \" | Double quote |
| \\ | Backslash |
| \b | Backspace |
| \f | Form feed |
| \n | New line |
| \r | Carriage return |
| \t | Horizontal tabulator |
| \v | Vertical tabulator |
| JavaScript String Methods | |
| charAt() | Return a character at a specified position inside a string |
| charCodeAt() | Give the unicode of character at that position |
| concat() | Concatenate (join) 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 with the last occurrence, searching backwards |
| 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 strings to lower case |
| toUpperCase() | Convert strings to upper case |
| valueOf() | Return the primitive value (that has no properties or methods) of a string object |
| REGULAR EXPRESSION SYNTAX 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 |
| \xdd | Latin character specified by a hexadecimal number dd |
| \udddd | Unicode character specified by a hexadecimal number dddd |
| Quantifiers | |
| n+ | Match any string that contains at least one n |
| n* | Any string that contains zero or more occurrences of n |
| n? | Any string that contains zero or one occurrences of n |
| n{X} | Any 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 |
| Number Properties | |
| MAX_VALUE | Maximum numeric value representable in JavaScript |
| MIN_VALUE | Smallest positive numeric value representable in JavaScript |
| NaN | The “Not-a-Number” value |
| NEGATIVE_INFINITY | Negative Infinity value |
| POSITIVE_INFINITY | Positive Infinity value |
| Number Methods | |
| toExponential() | Return a string with a rounded number written as exponential notation |
| toFixed() | Return string of a number with a specified number of decimals |
| toPrecision() | Return string of a number written with a specified length |
| toString() | Return a number as a string |
| valueOf() | Return a number as a number |
| Math Properties | |
| E | Euler’s number |
| LN2 | 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 | Square root of 2 |
| Math Methods | |
| abs(x) | Return the absolute (positive) value of x |
| acos(x) | Arccosine of x, in radians |
| asin(x) | Arcsine of x, in radians |
| atan(x) | 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) | Cosine of x (x is in radians) |
| exp(x) | Value of Ex |
| floor(x) | Value of x rounded down to its nearest integer |
| log(x) | Natural logarithm (base E) of x |
| max(x,y,z,...,n) | Number with highest value |
| min(x,y,z,...,n) | Number with lowest value |
| pow(x,y) | X to the power of y |
| random() | Random number between 0 and 1 |
| round(x) | Value of x rounded to its nearest integer |
| sin(x) | Sine of x (x is in radians) |
| sqrt(x) | Square root of x |
| tan(x) | Tangent of an angle |
| Dates | |
| Date() | Create a new date object with the current date and time |
| 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 |
| getDate() | Get the day of the month as a number (1-31) |
| getDay() | Get the weekday as a number (0-6) |
| getFullYear() | Get the year as a four digit number (yyyy) |
| getHours() | Get the hour (0-23) |
| getMilliseconds() | Get the millisecond (0-999) |
| getMinutes() | Get the minute (0-59) |
| getMonth() | Get the month as a number (0-11) |
| getSeconds() | Get the second (0-59) |
| getTime() | Get the time (milliseconds since January 1, 1970) |
| getUTCDate() | Day (date) of the month in the specified date according to universal time (also available for day, month, fullyear, hours, minutes etc.) |
| parse | Parse a string representation of a date, and return the number of milliseconds since January 1, 1970 |
| setDate() | Set the day as a number (1-31) |
| setFullYear() | Set the year (optionally month and day) |
| setHours() | Set the hour (0-23) |
| setMilliseconds() | Set the milliseconds (0-999) |
| setMinutes() | Set the minutes (0-59) |
| setMonth() | Set the month (0-11) |
| setSeconds() | Set the seconds (0-59) |
| setTime() | Set the time (milliseconds since January 1, 1970) |
| setUTCDate() | Set the day of the month for a specified date according to universal time (also available for day, month, fullyear, hours, minutes etc.) |
| DOM MODE
Node Properties |
|
| attributes | Live collection of all attributes registered to an element |
| baseURI | Absolute base URL of an HTML element |
| childNodes | Collection of an element’s child nodes |
| firstChild | First child node of an element |
| lastChild | Last child node of an element |
| nextSibling | Next node at the same node tree level |
| nodeName | Name of a node |
| nodeType | Type of a node |
| nodeValue | Value of a node |
| ownerDocument | Top-level document object for current node |
| parentNode | Parent node of an element |
| previousSibling | Node immediately preceding the current one |
| textContent | Textual content of a node and its descendants |
| Node Methods | |
| appendChild() | Add a new child node to an element as the last child node |
| cloneNode() | Clone HTML element |
| compareDocumentPosition() | Compare the document position of two elements |
| getFeature() | Return an object which implements the APIs of a specified feature |
| hasAttributes() | Return true if an element has any attributes, else return false |
| hasChildNodes() | Return true if an element has any child nodes, else return false |
| insertBefore() | Insert a new child node before a specified, existing child node |
| isDefaultNamespace() | Return true if a specified namespaceURI is the default, else return false |
| isEqualNode() | Check if two elements are equal |
| isSameNode() | Check if two elements are the same node |
| isSupported() | Return true if a specified feature is supported on the element |
| lookupNamespaceURI() | Return the namespaceURI associated with a given node |
| lookupPrefix() | Return a DOMString containing the prefix for a given namespaceURI, if present |
| normalize() | Join adjacent text nodes and remove empty text nodes in an element |
| removeChild() | Remove a child node from an element |
| replaceChild() | Replace a child node in an element |
| Element Methods | |
| getAttribute() | Return the specified attribute value of an element node |
| getAttributeNS() | Return string value of the attribute with the specified namespace and name |
| getAttributeNode() | Get the the specified attribute node |
| getAttributeNodeNS() | Return the attribute node for the attribute with the given namespace and name |
| getElementsByTagName() | Provide a collection of all child elements with the specified tag name |
| getElementsByTagNameNS() | Return a live HTML collection of elements with a certain tag name belonging to the given namespace |
| hasAttribute() | Return true if an element has any attributes, else return false |
| hasAttributeNS() | Provide a true/false value indicating whether the current element in a given namespace has the specified attribute |
| removeAttribute() | Remove a specified attribute from an element |
| removeAttributeNS() | Remove the specified attribute from an element within a certain namespace |
| removeAttributeNode() | Take away a specified attribute node and return the removed node |
| setAttribute() | Set or change the specified attribute to a specified value |
| setAttributeNS() | Add a new attribute or change the value of an attribute with the given namespace and name |
| setAttributeNode() | Set or change the specified attribute node |
| setAttributeNodeNS() | Add a new namespaced attribute node to an element |
| Browser Window Properties | |
| closed | Check whether a window has been closed or not and return true or false |
| defaultStatus | Set or return the default text in the statusbar of a window |
| document | Return the document object for the window |
| frames | Return all iframe elements in the current window |
| history | Provide the History object for the window |
| innerHeight | Inner height of a window’s content area |
| innerWidth | Inner width of the content area |
| length | Return the number of iframe elements in the window |
| location | Return the location object for the window |
| name | Set or return the name of a window |
| navigator | Return the Navigator object for the window |
| opener | Return a reference to the window that created the window |
| outerHeight | Outer height of a window, including toolbars/scrollbars |
| outerWidth | Outer width of a window, including toolbars/scrollbars |
| pageXOffset | Number of pixels by which the document has been scrolled horizontally |
| pageYOffset | Number of pixels by which the document has been scrolled vertically |
| parent | Parent window of the current window |
| screen | Return the Screen object for the window |
| screenLeft | Horizontal coordinate of the window (relative to screen) |
| screenTop | Vertical coordinate of the window |
| screenX | Same as screenLeft but needed for some browsers |
| screenY | Same as screenTop but needed for some browsers |
| self | Return the current window |
| status | Set or return the text in the statusbar of a window |
| top | Return the topmost browser window |
| Browser Window Methods | |
| alert() | Display an alert box with a message and an OK button |
| blur() | Remove focus from the current window |
| clearInterval() | Clear a timer set with setInterval() |
| clearTimeout() | Clear a timer set with setTimeout() |
| close() | Close the current window |
| confirm() | Display a dialog box with a message and OK and Cancel buttons |
| focus() | Set focus to the current window |
| moveBy() | Move a window relative to its current position |
| moveTo() | Move a window to a specified position |
| open() | Open a new browser window |
| print() | Print the content of the current window |
| prompt() | Display a dialog box that prompts the visitor for input |
| resizeBy() | Resize the window by the specified number of pixels |
| resizeTo() | Resize the window to a specified width and height |
| scrollBy() | Scroll the document by a specified number of pixels |
| scrollTo() | Scroll the document to specified coordinates |
| setInterval() | Call a function or evaluate an expression at specified intervals |
| setTimeout() | Call a function or evaluate an expression after a specified interval |
| stop() | Stop the window from loading |
| Screen Properties | |
| availHeight | Return the height of the screen (excluding the Windows Taskbar) |
| availWidth | Return the width of the screen (excluding the Windows Taskbar) |
| colorDepth | Return 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 |
| JAVASCRIPT EVENTS JavaScript Mouse Events |
|
| onclick | When user clicks on an element |
| oncontextmenu | When user right-clicks on an element to open a context menu |
| ondblclick | When user double-clicks on an element |
| onmousedown | When user presses a mouse button over an element |
| onmouseenter | When user moves pointer onto an element |
| onmouseleave | When user moves pointer away from an element |
| onmousemove | When user moves pointer while it is over an element |
| onmouseover | When user moves pointer onto an element or one of its children |
| onmouseout | When user moves pointer away from an element or one of its children |
| onmouseup | When user releases a mouse button while over an element |
| JavaScript Keyboard Events | |
| onkeydown | When user is pressing a key down |
| onkeypress | When user starts pressing a key |
| onkeyup | When user releases a key |
| JavaScript Frame Events | |
| onabort | When loading of media is aborted |
| onbeforeunload | Before the document is about to be unloaded |
| onerror | When an error occurs while loading an external file |
| onhashchange | When the anchor part of a URL has changed |
| onload | When an object has loaded |
| onpagehide | When user navigates away from a webpage |
| onpageshow | When user navigates to a webpage |
| onresize | When user resizes document view |
| onscroll | When user is scrolling an element’s scrollbar |
| onunload | When a page has unloaded |
| JavaScript Form Events | |
| onblur | When an element loses focus |
| onchange | When the content of a form element changes (for input, select, and textarea) |
| onfocus | When an element gets focus |
| onfocusin | When an element is about to get focus |
| onfocusout | When an element is about to lose focus |
| oninput | User input on an element |
| oninvalid | When an element is invalid |
| onreset | When a form is reset |
| onsearch | When a user types something in a search field (for input="search") |
| onselect | When user selects some text (for input and textarea) |
| onsubmit | When a form is submitted |
| JavaScript Drag Events | |
| ondrag | When user drags an element |
| ondragend | When user has finished dragging the element |
| ondragenter | When the dragged element enters a drop target |
| ondragleave | When the dragged element leaves the drop target |
| ondragover | When the dragged element is on top of the drop target |
| ondragstart | When user starts to drag an element |
| ondrop | Dragged element is dropped on the drop target |
| JavaScript Clipboard Events | |
| oncopy | When user copies content of an element |
| oncut | When user cuts an element’s content |
| onpaste | When user pastes content in an element |
| JavaScript Media Events | |
| onabort | When media loading is aborted |
| oncanplay | When browser can start playing media (e.g. a file has buffered enough) |
| oncanplaythrough | When browser can play through media without stopping |
| ondurationchange | When duration of media changes |
| onended | When media has reached its end |
| onerror | When an error occurs while loading an external file |
| onloadeddata | When media data is loaded |
| onloadedmetadata | When metadata (like dimensions and duration) is loaded |
| onloadstart | When browser starts looking for specified media |
| onpause | When media is paused either by user or automatically |
| onplay | When media has been started or is no longer paused |
| onplaying | When media is playing after having been paused or stopped for buffering |
| onprogress | When browser is in the process of downloading media |
| onratechange | When playing speed of media changes |
| onseeked | When user has finished moving/skipping to a new position in media |
| onseeking | When user starts moving/skipping |
| onstalled | When browser is trying to load unavailable media |
| onsuspend | When browser is intentionally not loading media |
| ontimeupdate | The playing position has changed (e.g. because of fast forward) |
| onvolumechange | When media volume has changed (including mute) |
| onwaiting | When media has paused but is expected to resume (for example, buffering) |
| Animation | |
| animationend | When CSS animation is complete |
| animationiteration | When CSS animation is repeated |
| animationstart | When CSS animation has started |
| Miscellaneous | |
| transitionend | When CSS transition is complete |
| onmessage | When a message is received through the event source |
| onoffline | When browser starts to work offline |
| ononline | When browser starts to work online |
| onpopstate | When the window’s history changes |
| onshow | When a menu element is shown as a context menu |
| onstorage | When a Web Storage area is updated |
| ontoggle | When user opens or closes the details element |
| onwheel | When mouse wheel rolls up or down over an element |
| ontouchcancel | When screen touch is interrupted |
| ontouchend | When user’s finger goes off touch screen |
| ontouchmove | When user drags a finger across the screen |
Explore JavaScript Further
We consider JavaScript one of the top programming languages to master for the future. And we recommend diving into advanced concepts like JavaScript array methods once you have a grasp of the basics of JavaScript.
Image Credit: Oskar Yildiz on Unsplash
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