[Javascript] Exemplu break + label

outerloop:
  for(var i = 0; i < 10; i++) {
    innerloop:
      for(var j = 0; j < 10; j++) {
          if (j > 3) break;             // Quit the innermost loop
          if (i == 2) break innerloop;  // Do the same thing
          if (i == 4) break outerloop;  // Quit the outer loop
          document.write("i = " + i + " j = " + j + "
");
      }
  }
  document.write("FINAL i = " + i + " j = " + j + "
"); 

Rezultatul fiind:

i = 0 j = 0
i = 0 j = 1
i = 0 j = 2
i = 0 j = 3
i = 1 j = 0
i = 1 j = 1
i = 1 j = 2
i = 1 j = 3
i = 3 j = 0
i = 3 j = 1
i = 3 j = 2
i = 3 j = 3
FINAL i = 4 j = 0 

[Learn JavaScript] Operatorul + este special

The + operator is a special one -- it gives priority to string operands over numeric operands. If either operand to + is a string (or an object), the other operand is converted to a string (or both operands are converted to strings) and concatenated, rather than added.

On the other hand, the comparison operators (<, >, <=, >=) perform string comparison only if both operands are strings. If only one operand is a string, JavaScript attempts to convert it to a number.

1 + 2        // Addition. Result is 3.
"1" + "2"    // Concatenation. Result is "12".
"1" + 2      // String Concatenation; 2 is converted to "2". Result is "12".
11 < 3       // Numeric comparison. Result is false.
"11" < "3"   // String comparison. Result is true.
"11" < 3     // Numeric comparison; "11" converted to 11. Result is false.
"one" < 3    // Numeric comparison; "one" converted to NaN. Result is false.
             // In JavaScript 1.1, this causes an error instead of NaN.

It is important to note that when the + operator is used with strings and numbers, it may not be associative. That is, the result may depend on the order in which operations are performed. This can be seen with examples like these:

s = 1 + 2 + " blind mice";   // Yields "3 blind mice"
t = "blind mice: " + 1 + 2;  // Yields "blind mice: 12"

The reason for this surprising difference in behavior is that the + operator works from left to right.

http://docstore.mik.ua/orelly/webprog/jscript/ch05_06.htm

Operatori in JavaScript

P	A	Operator	Operand type(s)	Operation performed
15	L	.	object, identifier	Property access
	L	[]	array, integer	Array index
	L	( )	function, arguments	Function call
	R	new	constructor call	Create new object
14	R	++	lvalue	Pre- or post-increment (unary)
	R	--	lvalue	Pre- or post-decrement (unary)
	R	-	number	Unary minus (negation)
	R	+	number	Unary plus (no-op)
	R	~	integer	Bitwise complement (unary)
	R	!	boolean	Logical complement (unary)
	R	delete	lvalue	Undefine a property (unary)
	R	typeof	any	Return data type (unary)
	R	void	any	Return undefined value (unary)
13	L	*, /, %	numbers	Multiplication, division, remainder
12	L	+, -	numbers	Addition, subtraction
	L	+	strings	String concatenation
11	L	<<	integers	Left shift
	L	>>	integers	Right shift with sign-extension
	L	>>>	integers	Right shift with zero extension
10	L	<, <=	numbers or strings	Less than, less than or equal
	L	>, >=	numbers or strings	Greater than, greater than or equal
	L	instanceof	object, constructor	Check object type
	L	in	string, object	Check whether property exists
9	L	==	any	Test for equality
	L	!=	any	Test for inequality
	L	===	any	Test for identity
	L	!==	any	Test for non-identity
8	L	&	integers	Bitwise AND
7	L	^	integers	Bitwise XOR
6	L	|	integers	Bitwise OR
5	L	&&	booleans	Logical AND
4	L	||	booleans	Logical OR
3	R	?:	boolean, any, any	Conditional operator (3 operands)
2	R	=	lvalue, any	Assignment
	R	*=, /=, %=, +=, -=, <<=, >>=, >>>=, &=, ^=, |=	lvalue, any	Assignment with operation
1	L	,	any	Multiple evaluation

The column labeled "P" specifies the precedence of each operator. Operator precedence controls the order in which operations are performed. Operators with higher numbers in the "P" column are performed before those with lower numbers.
Consider the following expression:

w = x + y*z; 

The multiplication operator * has a higher precedence than the addition operator +, so the multiplication is performed before the addition. Furthermore, the assignment operator = has the lowest precedence, so the assignment is performed after all the operations on the righthand side are completed.

Obs.

• In JavaScript all numbers are floating-point, so all divisions have floating-point results: 5/2 evaluates to 2.5, not 2. 
• While the modulo operator is typically used with integer operands, it also works for floating-point values. For example, -4.3 % 2.1 evaluates to -0.1. 

http://docstore.mik.ua/orelly/webprog/jscript/ch05_02.htm

Iphone CSS

Dimensiunile ecranului 320px cu 480px.

<meta name="viewport" content="width=320">

-> pentru a seta latimea ecranului (si implicit zoomul).

Putin javascript: 

window.scrollTo(0, 1) -> pentru a ascunde bara iphone-ului 

onorientationchange -> eveniment: la schimbarea orientarii mobilului ( portret <->orizontal ) 

http://css-tricks.com/video-screencasts/38-basics-tips-on-designing-for-the-iphone/