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--- notes:javascript_cheat_sheet [2026/06/12 23:58]
113.192.48.187 old revision restored (2026/06/04 14:43)
+++ notes:javascript_cheat_sheet [2026/06/13 11:28] (current)
114.119.132.52 old revision restored (2008/09/04 01:49)
@@ Line 1: / Line 1: @@
 ===== Javascript Cheat Sheet =====
-This is a summarized form of the [[http://www.w3schools.com/js/default.asp | JavaScript Tutorial]].
+This is a summarized form of the [[http://www.w3schools.com/js/default.asp | Javascript Tutorial]].
-For reference JavaScript specifications can be found [[http://developer.mozilla.org/en/JavaScript_Language_Resources | here]] .
+For reference Javascript specifications can be found [[http://developer.mozilla.org/en/JavaScript_Language_Resources | here]] .
 ==== What is Javascript ====
   * JavaScript is the most popular scripting language on the internet and works in all major browsers.
-  * It is a lightweight, interpreted, object-oriented language that is embedded into webpages to add interactivity.
-  * 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="text/javascript">
-<!--
-document.write("Hello World!");
-//-->
-</script> </code>
-  * 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="abc.js"></script>
-==== 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 >,>=,==, !=, a?b:c. It also uses === to test equality of value and type.
-==== Basic Structures ====
-  * if {} else if {} else {}
-  * for (var=start;var%%<=%%end;var=var+inc) {}
-  * while (condition) {}
-  * do {} while (condition) ;
-  * //break// and //continue// both valid in a loop.
-  * for (element in array) {}
-  * for (property in object) {}
-  * switch (n) { case 1: stmt; break; default: stmt; }
-  * function name(var1,var2,...) {}
-  * \", \n, \t, \r, \', \&, \\
-  * with (object) { } changes default object for fields.
-==== Events, Error Handling & Popups ====
-  *  try { throw "errname"; } catch(err) {}
-  * onerror=handleErr; handleErr(msg,url,linenum)
-  * if handleErr returns false, browser displays a standard error message in the JavaScript console.
-  * an alert box just has an OK button - alert("msg")
-  * a confirm box returns true if the user clicks OK, false if he clicks cancel - confirm("msg")
-  * a prompt box allows the user to enter a value. It returns true if the user clicks OK, false if he clicks cancel - prompt("msg","defaultvalue");
-  *  JavaScript functions can be registered to run on certain events (event="jscode" in an HTML element):
-    * onunload, onload (page or image), onresize, onabort
-    * onfocus, onblur, onclick, ondblclick
-    * onmouseover, onmouseout, onmousemove
-    * onchange, onsubmit, onreset, onselect
-    * onkeydown, onkeypress, onkeyup
-    * onmousedown, onmouseup
-==== JavaScript Objects ====
-  * Objects have properties and methods.
-  * Objects can be created directly <code javascript>
-personObj=new Object();
-personObj.firstname="John";
-personObj.newfirstname =
- function (new_firstname)
-   { this.firstname=new_firstname; } </code>
-  * Objects can be created using a template <code javascript>
-function person(firstname) {
-  this.firstname=firstname;
-  this.newfirstname =
-    function (new_firstname)
-    { this.firstname=new_firstname; }
-}
-myFather=new person("John");</code>
-  * Object methods can also be assigned by name e.g. <code javascript>
-function person(firstname)
-{
-  this.firstname=firstname;
-  this.newfirstname=newfirstname;
-}
-function newfirstname(new_firstname)
-{ this.firstname=new_firstname; } </code>
-==== Predefined Objects ====
-  * String objects have a length property and methods including: indexOf, match, replace
-  * new Date() creates a Date object (with today's date).
-  * Date objects include methods: getTime(epoch), setFullYear, toUTCString, getDay, getHours
-  * Date objects can be compared using <, > .
-  * To declare an array <code javascript> var mycars=new Array("Saab","Volvo","BMW");</code>
-  * Arrays have methods including: sort, concat, join.
-  * To sort an integer array, must use a function <code javascript> function intSort (a, b){ return a - b;}</code>
-  * 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.
-==== Advanced JavaScript ====
-  * navigator.appName/appVersion contain the browser name and version.
-  * document.cookie allows read and write access to cookie so to set a cookie <code javascript>
-function setCookie(c_name,value,expiredays)
-{
-  var exdate=new Date();
-  exdate.setDate(exdate.getDate()+expiredays);
-  document.cookie=c_name+ "=" +escape(value)+
-    ((expiredays==null) ? "" :
-     ";expires="+exdate.toGMTString());
-} </code>
-  * The onsubmit event can be used to validate a form.
-  * document.img_name.src ="pic.gif" changes an image.
-  * To change the content of a block with a given id : <code javascript>
-document.getElementById("block_id").innerHTML=txt;</code>
-  * To set or clear a timed action: <code javascript>
-var t=setTimeout("javascript statement",milliseconds);
-clearTimeout(t); </code>

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