Question: What's the difference between `|` and `||` in Javascript?

Furthermore, what's the difference between `&` and `&&`?

Answer: 
* `&` is [the bitwise AND operator](http://rx4ajax-jscore.com/resource/glossary/glossb.html#bitwise_and_operator)
* `|` is [the bitwise OR operator](http://rx4ajax-jscore.com/resource/glossary/glossb.html#bitwise_or_operator)
* `&&` is [the logical AND operator](http://www.devguru.com/technologies/ecmascript/quickref/logical_operators.html)
* `||` is [the logical OR operator](http://www.devguru.com/technologies/ecmascript/quickref/logical_operators.html)

The difference is that logical operators only consider each input at face value, treating them as whole, while [bitwise operators work at the bit level](http://en.wikipedia.org/wiki/Bitwise_operation):

```
var thetruth = false;
var therest = true;

var theuniverse = thetruth && therest; //false
var theparallel = thetruth && thetruth; //true

var theindifferent = thetruth || therest; //true
var theideal = thetruth || thetruth; // false

var thematrix = 5346908590;
var mrsmith = 2354656767;

var theoracle = thematrix & mrsmith; //202445230
var theone = thematrix | mrsmith; //7499120127

```
Single | is bit wise OR operator . 
If you do 2 | 3 , it converts to binary and performs OR operation.
 01
 11
Results in 11 equal to 3.

Where as || operator checks if first argument is true, if it is true it returns else it goes to other operator.
2 || 3 returns 2 since 2 is true.