Javascript Basics Part II

Statements

• break
• for
• switch
• throw
• try
• with

For statement

for (var name in object)
{
	if(object.hasOwnProperty(name))
	{
		// within the loop, name is the key of current memeber
		// object[name] is the current value
	}
}

Switch statement

• The switch value can be a string. Not restricted to integer
• The cast statements can be expressions, not just constants

Throw statement

throw new Error(reason);

throw 
{
	name: exceptionName,
	message: reason
}

Try statement

• Because we don’t have classes, we just have one catch clause. There cannot be multiple catch clauses.
• The javascript implementation can produce these exception names:
  • Error
  • EvalError
  • RangeError
  • SyntaxError
  • TypeError
  • URIError

try
{

}
catch(e)
{

}

With statement

• Ambiguous and error prone, don’t use it.

with (o)
{
	foo = null;
}

Either o.foo = null; or foo = null; depending on if foo is a global variable

Function statement

function name(parameters)
{

}

Var statement

• Types are not specified
• Initial values are optional

Scope

• Blocks do not have scopes, only function has scopes.
• Because of laziness while writing the compiler :)
• This is a mistake in language

Return statement

return expression; Or return;

• If there is no expression, then the return value is undefined
• Exception in constructors, return value is this