Are you ready?
10 questions to solve
- This quiz goes to full-screen once you press the Start button.
- At the end of the quiz, you are able to review all the questions that you answered wrong and see their explanations.
There is no typo in the code.
(function() {
console.log('Hello World!');
});(), hence it's body doesn't execute. This means that nothing is logged in the console, which goes with choice (B). For more info, refer to JavaScript Functions — IIFEs.callee property of the arguments object available inside a function contains a reference to the function itself, and can therefore be used to recursively call it. This goes with choice (B). For more info, refer to JavaScript Functions — arguments.callee.console.log(this === window);this as used in the global context returns back the window object. Hence, this === window evaluates to true, and thus the correct choice is (A). For more info, refer to JavaScript Functions — this.var x = 10;
var f2 = f;
var obj = {
x: 20,
f: f2
}
console.log(f());
console.log(f2());
console.log(obj.f());
function f() {
return this.x;
}Let's go step-by-step. First, a global variable x is created with the value 10. Next another variable f2 is created with the value f, which is a function accessible at this stage via functional hoisting. Next up, an object obj is created with a property x set to 20 and a property f set to f2.
In the first log, f() gets executed with this.x resolving down to the global variable x. Likewise, we get 10 logged. The second log is similar to the first log, hence we get another 10 logged. The last log calls obj.f(), likewise this.x inside the function resolves to obj.x which is 20. Hence, 20 gets logged.
Altogether, we get 10, 10 and 20 logged. This goes with choice (C). For more info, refer to JavaScript Functions — this.
function() {
}this.Hoisting.IIFEs.var sum = function localSum(a, b) {
return a + b;
}
console.log(typeof localSum);typeof localSum above returns 'undefined', and this goes with choice (A). For more info, refer to JavaScript Functions — Named function expressions.
