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| ===== Javascript Cheat Sheet ===== | ===== Javascript Cheat Sheet ===== | ||
| - | This is a summarized form of the [[http:// | + | This is a summarized form of the [[http:// |
| - | For reference | + | For reference |
| ==== What is Javascript ==== | ==== What is Javascript ==== | ||
| * JavaScript is the most popular scripting language on the internet and works in all major browsers. | * JavaScript is the most popular scripting language on the internet and works in all major browsers. | ||
| - | * It is a lightweight, | ||
| - | * JavaScript can read and write HTML page elements, react to events, validate data, create cookies. | ||
| - | * JavaScript was invented by Brendan Eich of Netscape but is now known officially as ECMAScript (current version is ECMA-262). | ||
| - | * A simple "Hello World" example <code html> | ||
| - | <script type=" | ||
| - | <!-- | ||
| - | document.write(" | ||
| - | //--> | ||
| - | </ | ||
| - | * JavaScript code may be located | ||
| - | * In the head - executed when called | ||
| - | * In the body - executed while loading | ||
| - | * In an external file called from either the head or the body e.g. <script src=" | ||
| - | |||
| - | ==== Basic Syntax ==== | ||
| - | |||
| - | * JavaScript is case-sensitive. | ||
| - | * Statements may omit the final semi-colon but should not. | ||
| - | * Blocks may be grouped together using curly braces { }. | ||
| - | * JavaScript uses java-style comments: %%//%% and /* */. | ||
| - | * JavaScript variables are case-sensitive and must begin with a letter or underscore. | ||
| - | * Variables are automatically declared when first used but should be explicitly declared using e.g. var a = 5; | ||
| - | * JavaScript uses standard C/Java operators e.g. +-*/%, ++, +=, &&, ||, !, + (concatenation). | ||
| - | * JavaScript uses C/Java comparators >,> | ||
| - | |||
| - | ==== Basic Structures ==== | ||
| - | |||
| - | * if {} else if {} else {} | ||
| - | * for (var=start; | ||
| - | * while (condition) {} | ||
| - | * do {} while (condition) ; | ||
| - | * //break// and // | ||
| - | * for (element in array) {} | ||
| - | * for (property in object) {} | ||
| - | * switch (n) { case 1: stmt; break; default: stmt; } | ||
| - | * function name(var1, | ||
| - | * \", \n, \t, \r, \', \&, \\ | ||
| - | |||
| - | ==== Events, Error Handling and Popups ==== | ||
| - | * try { throw " | ||
| - | * onerror=handleErr; | ||
| - | * if handleErr returns false, browser displays a standard error message in the JavaScript console. | ||
| - | |||
| - | * an alert box just has an OK button - alert(" | ||
| - | * a confirm box returns true if the user clicks OK, false if he clicks cancel - confirm(" | ||
| - | * a prompt box allows the user to enter a value. It returns true if the user clicks OK, false if he clicks cancel - prompt(" | ||
| - | |||
| - | * JavaScript functions can be registered to run on certain events (event=" | ||
| - | * onunload, onload (page or image), onresize, onabort | ||
| - | * onfocus, onblur, onclick, ondblclick | ||
| - | * onmouseover, | ||
| - | * onchange, onsubmit, onreset, onselect | ||
| - | * onkeydown, onkeypress, onkeyup | ||
| - | * onmousedown, | ||
| - | |||
| - | ==== JavaScript Objects ==== | ||
| - | * Objects have properties and methods. | ||
| - | * String objects have a length property and methods including: indexOf, match, replace | ||
| - | * new Date() creates a Date object (with today' | ||
| - | * Date objects include methods: getTime(epoch), | ||
| - | * Date objects can be compared using <, > . | ||
| - | * To declare an array <code html> var mycars=new Array(" | ||
| - | * Arrays have methods including: sort, concat, join. | ||
| - | * To sort an integer array, must use a function <code html> function intSort (a, b){ return a - b; | ||
| - | * The Math object contains common math routines: round, random, e, pi etc. | ||
| - | * The RegExp object supports regexp creation and searching including methods: test (t/f), exec, compile (alter). | ||
| - | * HTML DOM objects allow access to browser and webpage. | ||