Javascript cheatsheet for beginners


if (condition) {

//what to do if condition is met



//what to do if condition is not met



var person = “John Doe”;


\’   -Single quote

\”   -Double quote

\\   – Backslash

\b  – Backspace

\t   – Horizontal tabulator

\n   -New line


  • 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 ft 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
  • toUpperCase() – Convert strings to uppercase
  • valueOf() – Returns the primitive value (that has no properties or methods) of a string object


  • 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


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



  • 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
  • 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


  • onkeydown- When the user is pressing a key down
  • onkeypress – The moment the user starts pressing a key
  • onkeyup –  The user releases a key


  • 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
  • onreset –  A form is reset
  • onsearch – The user writes something in a search field (for <input=”search”>)
  • onsubmit – A form is submitted

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