var a = {1:'one',2:'two',3:'three'}; var b = Object.keys(a); What's the value of b?

What is the value of x? var x = '1'+2+3;

Which orders can be performed with the Array prototype 'sort()' callback?

null === undefined

When an array index goes out of bounds, what is returned?

Which invokes a user-defined object constructor function?

Which statement is true about the "async" attribute for the HTML script tag?

Why is it usually better to work with Objects instead of Arrays to store a collection of records?

Which variable is an implicit parameter for every function in JavaScript?

Which of the following is not a keyword in JavaScript?

Which of the following values is not a Boolean false?