When iterating through an objects properties, which function should be used to check each property?

In the HTML code a div is present

To define var1 = 'AAAAAAAAAAAAAAAAAAAA' //20 times A Which of the following could be used

Which one returns current millisecond count?

what will be the VALUE and TYPE of i? var i = -Infinity;

Which is the optimal method of executing a for-loop?

Which correctly explains the difference between a 'for...in' and a 'for' loop?

Which one checks if an object has a specific property?

What value would JavaScript assign to an uninitialized array element?

If an image is placed styled with z-index=-1 and a text paragraph is overlapped with it, which one will be displayed on top?

Consider the three variables: someText = 'JavaScript1.2'; pattern = /(\w+)(\d)\.(\d)/i; outCome = pattern.exec(someText); What does outCome[0] contain?