Javascript coding style

Javascript coding styles

Rule 1: use var . (avoid globals) 

Rule 2: Use THIS_IS_A_CONSTANT

Rule 3: Use Semicolons and the end of variable and function expressions ( and not function declarations) 

Rule 4 : function declarations within blocks
//DONT        if(x){
                function foo()
              }

// DO       if(x){
              var foo = function(){}
            }

Rule 4 :standards are preferred
string.charAt(3) is preferred than string[3]


Rule 5: attaching methods and properties use prototype . 
Foo.prototype.bar = function(){ ..... }

Rule 6 : to remove the property use 'null'
this.property = null is preferred over delete this.property;
coz : In modern JavaScript engines, changing the number of properties on an object is much slower than reassigning the values.

Rule 7 : Think twice when using closures as they can cause memory leaks
http://google-styleguide.googlecode.com/svn/trunk/javascriptguide.xml?showone=Closures#Closures

Rule 8 : Avoid Evals
/TODO/

Rule 9 : use for-in loop only for iterating over objects and hash maps
In arrays its wrong
eg: var a = [ 1, 3, 4 ]; 
    a.foo = 'wine';
    for ( var key in a ) console.log(a[key]);

Rule 10 : Do not use multiline string literals instead use concat operation

Rule 11 : use Array and object literals instead of Array and object constructors

Rule 12 : Avoid modifying builtin prototypes. They are DANGEROUS

Rule 13 : In general, use functionNamesLikeThis, variableNamesLikeThis, ClassNamesLikeThis, EnumNamesLikeThis, methodNamesLikeThis, CONSTANT_VALUES_LIKE_THIS, foo.namespaceNamesLikeThis.bar, and filenameslikethis.js.
  Private properties and methods should be named with a trailing underscore.
  Protected properties and methods should be named without a trailing underscore (like public ones).