Getting Around

Question 1

When can a “For” loop be used?

Advantages?

Answer 1

Technique for Array iteration

+ uses iteration variable instead of accessing every property on every loop

+ Iteration var can be declared within the loop

Question 2

When is a ‘For … in’ loop used?
How does it work?
Important efficiency tip?

Answer 2

Technique for enumeration of properties in objects (non-arrays)

• accesses every property of the object
• Test with object.hasOwnProperty( ) to skip prototype properties

for (var i in myThing) {
		if(myThing.hasOwnProperty(i){
			//loop stuff
		}
}