Javascript Assessment Test

How well do you know the Javascript language? Take the JSAT and find out.

The Javascript Assessment Test (85 questions)

Time limit: 45 minutes (All answers found at end of book)

Select the best answer for each question.

1. The statement below creates a new context.
eval?.("'use strict'; function f(){console.log('hello')}")

a. true
b. false

2. Under non-strict mode, a statement x = 40 performs what action?

a. variable declaration
b. variable assignment
c. variable declaration or assignment
d. variable declaration and assignment
e. none of the above

3. What best describes the type of relationship between the variable named i and the anonymous function in the code below:

var a = [];
for (var i=0; i<5; ++i){
a[i] = function(){
console.log(i);
}
}

a. one-to-one
b. one-to-many
c. many-to-one
d. many-to-many
e. none of the above

4. Which of the options below would solve the script error?

function f(){
this.msg = "hello"
}

f.prototype.greet = function(name){
console.log(`${this.msg}, ${name}`)
} }

const obj = new f()

setTimeout(obj.greet, 1000, "world!")


a. iteration or recursion
b. block or constant variable
c. function wrapper or reference
d. call or apply method
e. none of the above

5. The var keyword creates properties on the window object.
a. true
b. false

6. Every object instance has a prototype property.
a. true
b. false

7. The strict mode is automatically in effect for a given script.
a. true
b. false

8. Using the let keyword creates properties on the global object.
a. true
b. false

9. How many closures or contexts are created in the given script?

var list = [];

f();

list.forEach(fn=>fn());

function f(){
var strings = ["romeo", "sierra", "tango"];
for (let i = 0; i < 3; i++){
list[i] = ()=>console.log(list[i], strings[i]);
}
}


a. 5
b. 9
c. 11
d. 7
e. none of the above

10. Every object instance has a __prototype__ property.
a. true
b. false

11. The formal argument of the given dynamic function forms a closure with the custom Date() function.

(function(){
function Date(){
console.log(“Have a happy date!”);
}
new Function(“Date”, "return Date()")(Date);
})();

a. true
b. false

12. How many variables exist while the function f is running?

var x = 0;
var y = 1;

function f() {
var x = y;
}

f();

a. 2
b. 3
c. 5
d. 4
e. none of the above