EMT Practice Test

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Question1: A developer receives a comment from the Tech Lead that the code given below has error:
const monthName = 'July';
const year = 2019;
if(year === 2019) {
monthName = 'June';
}
Which line edit should be made to make this code run?

Question2: GIven a value, which three options can a developer use to detect if the value is NaN?
Choose 3 answers !

Question3: Which statement phrases successfully?

Question4: Which statement accurately describes an aspect of promises?

Question5: A developer has the following array of student test grades:
Let arr = [ 7, 8, 5, 8, 9 ];
The Teacher wants to double each score and then see an array of the students who scored more than 15 points.
How should the developer implement the request?

Question6: A test has a dependency on database.query. During the test the dependency is replaced with an object called database with the method, query, that returns an array. The developer needs to verify how many times the method was called and the arguments used each time.
Which two test approaches describe the requirement?
Choose 2 answers

Question7: Universal Containers (UC) notices that its application that allows users to search for accounts makes a network request each time a key is pressed. This results in too many requests for the server to handle.
* Address this problem, UC decides to implement a debounce function on string change handler.
What are three key steps to implement this debounce function?
Choose 3 answers:

Question8: Refer to the code below:

Considering that JavaScript is single-threaded, what is the output of line 08 after the code executes?

Question9: Refer to the code below:
Let str = 'javascript';
Str[0] = 'J';
Str[4] = 'S';
After changing the string index values, the value of str is 'javascript'. What is the reason for this value:

Question10: Refer to the code below:
<html lang="en">
<table onclick="console.log(Table log');">
<tr id="row1">
<td>Click me!</td>
</tr>
<table>
<script>
function printMessage(event) {
console.log('Row log');
}
Let elem = document.getElementById('row1');
elem.addEventListener('click', printMessage, false);
</script>
</html>
Which code change should be made for the console to log only Row log when 'Click me! ' is clicked?

Question11: Given the code below:
const copy = JSON.stringify([ new String(' false '), new Bollean( false ), undefined ]); What is the value of copy?

Question12: Given the following code:
document.body.addEventListener(' click ', (event) => {
if (/* CODE REPLACEMENT HERE */) {
console.log('button clicked!');
)
});
Which replacement for the conditional statement on line 02 allows a developer to correctly determine that a button on page is clicked?

Question13: A developer is creating a simple webpage with a button. When a user clicks this button for the first time, a message is displayed.
The developer wrote the JavaScript code below, but something is missing. The message gets displayed every time a user clicks the button, instead of just the first time.
01 function listen(event) {
02 alert ( 'Hey! I am John Doe') ;
03 button.addEventListener ('click', listen);
Which two code lines make this code work as required?
Choose 2 answers

Question14: developer is trying to convince management that their team will benefit from using Node.js for a backend server that they are going to create. The server will be a web server that handles API requests from a website that the team has already built using HTML, CSS, and JavaScript.
Which three benefits of Node.js can the developer use to persuade their manager?
Choose 3 answers:

Question15: A developer creates a generic function to log custom messages in the console. To do this, the function below is implemented.
01 function logStatus(status){
02 console./*Answer goes here*/{'Item status is: %s', status};
03 }
Which three console logging methods allow the use of string substitution in line 02?

Question16: Refer to the following code:
<html lang="en">
<body>
<div onclick = "console.log('Outer message') ;">
<button id ="myButton">CLick me<button>
</div>
</body>
<script>
function displayMessage(ev) {
ev.stopPropagation();
console.log('Inner message.');
}
const elem = document.getElementById('myButton');
elem.addEventListener('click' , displayMessage);
</script>
</html>
What will the console show when the button is clicked?

Question17: Which two console logs output NaN?
Choose 2 answers | |

Question18: A developer has a web server running with Node.js. The command to start the web server is node server.js. The web server started having latency issues. Instead of a one second turnaround for web requests, the developer now sees a five second turnaround.
Which command can the web developer run to see what the module is doing during the latency period?

Question19: Which option is true about the strict mode in imported modules?

Question20: Consider type coercion, what does the following expression evaluate to?
True + 3 + '100' + null

Question21: Refer to the code below:
function foo () {
const a =2;
function bat() {
console.log(a);
}
return bar;
}
Why does the function bar have access to variable a ?

Question22: Which statement accurately describes the behaviour of the async/ await keyworks ?

Question23: Refer to the code below:
let timeFunction =() => {
console.log('Timer called.");
};
let timerId = setTimeout (timedFunction, 1000);
Which statement allows a developer to cancel the scheduled timed function?

Question24: Given two expressions var1 and var2. What are two valid ways to return the logical AND of the two expressions and ensure it is data type Boolean ?
Choose 2 answers:

Question25: Which two code snippets show working examples of a recursive function?
Choose 2 answers

Question26: Refer to the following code:
function test (val) {
If (val === undefined) {
return 'Undefined values!' ;
}
if (val === null) {
return 'Null value! ';
}
return val;
}
Let x;
test(x);
What is returned by the function call on line 13?

Question27: Refer to the code below?
Let searchString = ' look for this ';
Which two options remove the whitespace from the beginning of searchString?
Choose 2 answers

Question28: Which code statement below correctly persists an objects in local Storage ?

Question29: Refer to code below:
Let productSKU = '8675309' ;
A developer has a requirement to generate SKU numbers that are always 19 characters lon, starting with 'sku', and padded with zeros.
Which statement assigns the values sku0000000008675309 ?

Question30: Refer to the following array:
Let arr1 = [ 1, 2, 3, 4, 5 ];

Which two lines of code result in a second array, arr2 being created such that arr2 is not a reference to arr1?

Question31: Refer to the following code:
Let obj ={
Foo: 1,
Bar: 2
}
Let output =[],
for(let something in obj{
output.push(something);
}
console.log(output);
What is the output line 11?

Question32: myArraym can have one level, two levels, or more levels.
Which statement flattens myArray when it can be arbitrarily nested?

Question33: Which two console logs outputs NaN ?
Choose 2 answers

Question34: A developer creates a class that represents a blog post based on the requirement that a Post should have a body author and view count.
The Code shown Below:
Class Post {
// Insert code here
This.body =body
This.author = author;
this.viewCount = viewCount;
}
}
Which statement should be inserted in the placeholder on line 02 to allow for a variable to be set to a new instanceof a Post with the three attributes correctly populated?

Question35: Given the following code:
Counter = 0;
const logCounter = () => {
console.log(counter);
);
logCounter();
setTimeout(logCOunter, 1100);
setInterval(() => {
Counter++
logCounter();
}, 1000);
What is logged by the first four log statements?

Question36: developer removes the HTML class attribute from the checkout button, so now it is simply:
<button>Checkout</button>.
There is a test to verify the existence of the checkout button, however it looks for a button with class= "blue". The test fails because no such button is found.
Which type of test category describes this test?

Question37: Refer to code below:
function Person() {
this.firstName = 'John';
}
Person.prototype ={
Job: x => 'Developer'
};
const myFather = new Person();
const result =myFather.firstName + ' ' + myFather.job();
What is the value of the result after line 10 executes?

Question38: A developer is leading the creation of a new browser application that will serve a single page application. The team wants to use a new web framework Minimalsit.js. The Lead developer wants to advocate for a more seasoned web framework that already has a community around it.
Which two frameworks should the lead developer advocate for?
Choose 2 answers

Question39: developer has a web server running with Node.js. The command to start the web server is node server,js. The web server started having latency issues. Instead of a one second turn around for web requests, the developer now sees a five second turnaround, Which command can the web developer run to see what the module is doing during the latency period?

Question40: A developer is setting up a new Node.js server with a client library that is built using events and callbacks.
The library:
* Will establish a web socket connection and handle receipt of messages to the server
* Will be imported with require, and made available with a variable called we.
The developer also wants to add error logging if a connection fails.
Given this info, which code segment shows the correct way to set up a client with two events that listen at execution time?

Question41: Refer to following code block:
Let array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,];
Let output =0;
For (let num of array){
if (output >0){
Break;
}
if(num % 2 == 0){
Continue;
}
Output +=num;
What is the value of output after the code executes?

Question42: A class was written to represent items for purchase in an online store, and a second class Representing items that are on sale at a discounted price. THe constructor sets the name to the first value passed in. The pseudocode is below:
Class Item {
constructor(name, price) {
... // Constructor Implementation
}
}
Class SaleItem extends Item {
constructor (name, price, discount) {
...//Constructor Implementation
}
}
There is a new requirement for a developer to implement a description method that will return a brief description for Item and SaleItem.
Let regItem =new Item('Scarf', 55);
Let saleItem = new SaleItem('Shirt' 80, -1);
Item.prototype.description = function () { return 'This is a ' + this.name; console.log(regItem.description()); console.log(saleItem.description()); SaleItem.prototype.description = function () { return 'This is a discounted ' + this.name; } console.log(regItem.description()); console.log(saleItem.description()); What is the output when executing the code above ?

Question43: A developer is asked to fix some bugs reported by users. To do that, the developer adds a breakpoint for debugging.
Function Car (maxSpeed, color){
This.maxspeed =masSpeed;
This.color = color;
Let carSpeed = document.getElementById(' CarSpeed');
Debugger;
Let fourWheels =new Car (carSpeed.value, 'red');
When the code execution stops at the breakpoint on line 06, which two types of information are available in the browser console ?
Choose 2 answers:

Question44: Considering type coercion, what does the following expression evaluate to?
True + '13' + NaN

Question45: A developer wants to leverage a module to print a price in pretty format, and has imported a method as shown below:
Import printPrice from '/path/PricePrettyPrint.js';
Based on the code, what must be true about the printPrice function of the PricePrettyPrint module for this import to work ?

Question46: Universal Containers (UC) just launched a new landing page, but users complain that the website is slow. A developer found some functions any that might cause this problem. To verify this, the developer decides to execute everything and log the time each of these three suspicious functions consumes.
Which function can the developer use to obtain the time spent by every one of the three functions?

Question47: A developer is trying to handle an error within a function.
Which code segment shows the correct approach to handle an error without propagating it elsewhere?
A)

B)

C)

D)

Question48: Refer to the code:

Given the code above, which three properties are set pet1?
Choose 3 answers:

Question49: Refer to HTML below:
<p> The current status of an Order: <span id ="status"> In Progress </span> </p>.
Which JavaScript statement changes the text 'In Progress' to 'Completed' ?

Question50: The developer has a function that prints "Hello" to an input name. To test this, thedeveloper created a function that returns "World". However the following snippet does not print " Hello World".

What can the developer do to change the code to print "Hello World" ?

Question51: is below:
<input type="file" onchange="previewFile()">
<img src="" height="200" alt="Image Preview..."/>
The JavaScript portion is:
01 function previewFile(){
02 const preview = document.querySelector('img');
03 const file = document.querySelector('input[type=file]').files[0];
04 //line 4 code
05 reader.addEventListener("load", () => {
06 preview.src = reader.result;
07 },false);
08 //line 8 code
09 }
In lines 04 and 08, which code allows the user to select an image from their local computer , and to display the image in the browser?

Question52: Refer to the code below:

Which value can a developer expect when referencing country,capital,cityString?

Question53: A developer creates a simple webpage with an input field. When a user enters text in the input field and clicks the button, the actual value of the field must be displayed in the console.
Here is the HTML file content:
<input type =" text" value="Hello" name ="input">
<button type ="button" >Display </button>
The developer wrote the javascript code below:
Const button = document.querySelector('button');
button.addEvenListener('click', () => (
Const input = document.querySelector('input');
console.log(input.getAttribute('value'));
When the user clicks the button, the output is always "Hello".
What needs to be done make this code work as expected?

Question54: A developer has code that calculates a restaurant bill, but generates incorrect answers while testing the code:
function calculateBill ( items ) {
let total = 0;
total += findSubTotal(items);
total += addTax(total);
total += addTip(total);
return total;
}
Which option allows the developer to step into each function execution within calculateBill?

Question55: Refer to code below:
Let first = 'who';
Let second = 'what';
Try{
Try{
Throw new error('Sad trombone');
}catch (err){
First ='Why';
}finally {
Second ='when';
} catch (err) {
Second ='Where';
}
What are the values for first and second once the code executes ?

Question56: Considering the implications of 'use strict' on line 04, which three statements describe the execution of the code?
Choose 3 answers

Question57: Given the following code:

is the output of line 02?

Question58: A developer has a formatName function that takes two arguments, firstName and lastName and returns a string. They want to schedule the function to run once after five seconds.
What is the correct syntax to schedule this function?

Question59: A developer has an ErrorHandler module that contains multiple functions.
What kind of export be leverages so that multiple functions can be used?