Which event fires whenever a control loses focus?

(function( ) { var x = foo( ); function foo( ){ return 'foobar' }; return x; })( ); What does this function return?

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

What does the following expression evaluate to? [] == [];

How do you import the lodash library making it top-level Api available as the "_" variable?

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?