Which function of the Object constructor with regard to JavaScript 1.8 returns the array of names of only enumerable properties of the given object?

In relation to object oriented JavaScript, which option can be used as the value of F.prototype?

In relation to sealing an object globally, which methods returns true if adding, removing, and changing properties is forbidden and all the current properties are configurable: false, writable: false?

Using DATE object which call a function based on elapsed time?

var a = [2, 5, 12, 16, 23, 35]; XXXX function abc( YYYY ) { return val > 20; } Which option will replace XXXX and YYYY in order to generate 4 as an output?

What's the output? var str = /u/.exec('I am the best friend!'); console.log(str);

Which will determine if the user's browser is named 'Netscape'?

Which is used to solve the problem of enumerations in JavaScript?

Which is an invalid function declaration?

Which is not a valid JavaScript operator?

Best reason for not using 'for...in' with array iteration?