master in javascript
DESCRIPTION
deeply understand javascript. http://neticy.com http://www.joke4me.comTRANSCRIPT
JavaScript The World's Most Misunderstood Programming Language
http://www.neticy.comhttp://[email protected]
Basic knowledge
Dynamic language and functional language
JavaScript frameworks and applications
Debug and experiences of development
Basic Knowledge
Literal notation
Keywords
Functions
OOP
DOM/HTML
Literal notation in languages
A literal value is any part of a statement or expression that is to be used exactly as it is, rather than as a variable or a script element.
You use literals to represent values in JavaScript. These are fixed values, not variables, that you literally provide in your script. This section describes the following types of literals:
① Array Literals② Boolean Literals③ Floating-Point Literals④ Integers⑤ Object Literals (JSON)⑥ String Literals⑦ Regex Literals
e.g. PHP/Java/C#: String, Integer, Boolean. Python: String, Dictionary , List, Tuple
typeof
instanceof
this
in
undefined /null
delete
try/catch/finally/throw
|| &&
Keywords
typeof " number" 、 "string" 、 "boolean" 、 "object" 、 "function" 、 "undefined “.
If you just declare a variable, the default value of the variable is ‘undefined’.Always wrong if you are using an undefined variable.
e.g. var s = s || {};
|| Return the “true-like” variable, if both of them are true, return the first. ( Equal ? : )
&& Return the “false-like” variable, if both of them are true, return the second.
instanceof Check if the instance is initialized from that function/class.Check if the prototype of some class/function is in the chain of some object.
e.g. obj instanceof ClassA
Since every object has a prototype chain, the operation of “instanceof” is to check if the ClassA’s prototype is in the chain of obj.
So it could be “true” for many Class to one object.
Code snippet
Every object has a constructor property.Every function/class has a prototype property which is an object,that is to say, it is an instance of function(class).
Discussion: how to check if a variable is array?
in
Return a boolean value which specifies if the first variable is a property/element of the second variable.
console.log(‘2’ in [1,2,3]); console.log(‘join’ in [1,2,3]);console.log(‘top’ in window);
undefined/null
If you just declare a variable, there the value of the variable is ‘undefined’.Null is defined, the value of null is null.
var d; if(d == undefined) console.log('fff');
delete
Make a variable undefined.Delete a property of an object.
var a = ‘tt’; delete a;
try/catch/finally/throw
try { aaa ;} catch(e) { console.log(e); }finally { console.log('ff');}
It is not a good idea to hide an error only if you know what you are doing.
throw Raise an exception.
this
Dynamic language / Lazy evaluation
“this” means what this is.
Compare the differences of “this” in JavaScript/PHP/C#
Change ‘this’ via “apply” and “call” functions.
More detail will be the code analysis.
Trivial Code Snippet
Functions
Execute function
setTimeout/setInterval
eval
call/apply
Execute function
call/apply
setTimeout/setInterval
Mutil threads simulation in JavaScript.
Animate effect in JavaScript.
eval
apply/call
Specify a new current instance as the ‘this’ object.
The difference of them is the arguments.
{prototype library source code}
bind: function() {
if (arguments.length < 2 && Object.isUndefined(arguments[0])) return this;
var __method = this, args = $A(arguments), object = args.shift();
return function() {
return __method.apply(object, args.concat($A(arguments)));
}
}
a.bind(b, …);
Source Code Analysis
Inheritance and creating class in Prototype Library.
OOP/Inheritance
There are 3 ways to implement inheritance.
①prototype chain
②Properties copy
③Using apply/call functions
Source Code Analysis
Inheritance in YUI and Mootools
JScript (IE)SpiderMonkey(FF)JavaScriptCore(Safari)linear_b(Opera)
DOM/HTML
JavaScript Engine
While JavaScript is the programming language which will allow you to
operate on the DOM objects and to manipulate them programmatically, the
DOM will provide you with methods and properties to retrieve, modify,
update, and delete parts of the document you are working on.
If a web page were a piece of imported Swedish furniture, the DOM would
be the illustrations of the parts - the shelves, bolts, Allen wrenches and
screwdrivers.
The Document Object Model, a language-neutral set of interfaces
Keywords: W3C DOM Level1 and DOM Level2, XML, SAX
HTML DOM STRUCTURE
Html type nodeType name nodeType value
Element Node.ELEMENT_NODE 1 Element Node
Text Node.TEXT_NODE 3 Text Node
Document Node.DOCUMENT_NODE 9 document
Comment Node.COMMENT_NODE 8 Comment
DocumentFragment Node.DOCUMENT_FRAGMENT_NODE 11 Fragment
Attr Node.ATTRIBUTE_NODE 2 Attribute
The NodeType and NodeType Value
e.g. alert(document.nodeType);
ELEMENT_NODE 1
ATTRIBUTE_NODE 2
TEXT_NODE 3
CDATA_SECTION_NODE 4
ENTITY_REFERENCE_NODE 5
ENTITY_NODE 6
PROCESSING_INSTRCTION_NODE 7
COMMENT_NODE 8
DOCUMENT_NODE 9
DOCUMENT_TYPE_NODE 10
DOCUMENT_FRAGMENT_NODE 11
NOTATION_NODE 12
All The NodeType and NodeType Value
createAttribute()createComment()createElement()createTextNode()getElementById()getElementsByTagName()
Document Methods
getAttribute()getAttributeNode()getElementsByTabName()hasAttribute()removeAttribute()removeAttributeNode()setAttribute()setAttributeNode()
Element Methods
attributeschildNodesfirstChildlastChildnextSiblingnodeNamenodeTypeparentNodepreviousSibling
appendChild()cloneNode()hasChildNodes()insertBefore()removeChild()replaceChild()
Node Properties & Methods
What’s the differences between Node and Element ?
The theory of DOM can be applied to other every dom manipulation, and other languages.
e.g. XML, XHTML, WML…e.g. PHP, Java, C#...
Ref erence: http://www.w3schools.com
