Question 1

Refer to the code below: https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/CRT-600/page_34_img_1.jpg Line 05 causes an error. What are the values of greeting and salutation once code completes?

Accepted Answer

A

Explanation: The code initializes greeting to 'Hello' and salutation to 'Hello, Hello'. The try...catch block is then encountered. Line 05, let salutation = 'I say ' + greeting;, attempts to re-declare the salutation variable, which was already declared with let in the same scope. This action results in a SyntaxError. SyntaxErrors are detected during the initial parsing phase of the script, before any code is executed. A try...catch statement can only handle runtime errors, not parse-time errors. Consequently, the entire try block is deemed invalid and is never executed. The assignment greeting = 'Goodbye'; on line 04 does not occur. The program halts or skips the invalid block, leaving the variables with the values they were assigned before the try statement.

Question 2

A developer has the function, shown below, that is called when a page loads.
function onload() {
console.log(“Page has loaded!”);
}
Where can the developer see the log statement after loading the page in the browser?

Accepted Answer

C

Explanation: The console.log() function is a client-side JavaScript method used for debugging. It writes a message to the web console, which is a standard feature within the developer tools of modern web browsers. When the onload function executes in the browser, the string "Page has loaded!" is sent specifically to this console interface, not to the server, the performance profiler, or the visible webpage content. This tool is fundamental for developers to inspect code execution and variable states.

Question 3

A developer needs to test this function:
01 const sum3 = (arr) => (
02 if (!arr.length) return 0,
03 if (arr.length === 1) return arr[0],
04 if (arr.length === 2) return arr[0] + arr[1],
05 return arr[0] + arr[1] + arr[2],
06 );
Which two assert statements are valid tests for the function?
Choose 2 answers

Accepted Answer

A, C

Explanation: The console.assert() method is used to verify that a given expression is true. The entire expression to be evaluated must be passed as the first argument. The correct syntax for testing a function's return value is console.assert(functionCall() == expectedValue). Options A and C correctly place the entire comparison expression inside the console.assert() call. Although the sum3 function is called with non-array arguments (e.g., sum3(-3, 2) instead of sum3([-3, 2])), causing it to return 0 and the assertions to fail, the statements themselves are structurally valid as tests. A failing assertion is a valid and useful test result.

Question 4

Refer to the code below:
Const resolveAfterMilliseconds = (ms) => Promise.resolve (
setTimeout (( => console.log(ms), ms ));
Const aPromise = await resolveAfterMilliseconds(500);
Const bPromise = await resolveAfterMilliseconds(500);
Await aPromise, wait bPromise;
What is the result of running line 05?

Accepted Answer

B

Explanation: The provided code will fail to execute due to multiple fatal syntax errors on line 05: Await aPromise, wait bPromise;. First, the await operator must be in all lowercase. Second, wait is not a valid keyword or operator in JavaScript. These issues will cause the JavaScript engine to throw a SyntaxError during the parsing phase, which occurs before any code is executed. Consequently, the asynchronous functions on the preceding lines will not be invoked, and neither promise will run.

Question 5

Refer to the code below: https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/CRT-600/page_86_img_1.jpg What is the output of this function when called with an empty array?

Accepted Answer

B

Explanation: The function utilizes the Array.prototype.reduce() method. The reduce() method executes a user-supplied "reducer" callback function on each element of the array, in order, passing in the return value from the calculation on the preceding element. The final result of running the reducer across all elements of the array is a single value. The syntax for reduce() includes an optional initialValue. If an initialValue is provided and the array is empty, the callback function is never executed, and the initialValue is returned. In this code, the function is called with an empty array [], and the initialValue is 5. Therefore, the reduce method returns 5.

Question 6

Given the following code: https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/CRT-600/page_83_img_1.jpg What will be the first four numbers logged?

Accepted Answer

B

Explanation: The code snippet provided in the image is incomplete for answering the question, as it contains no console.log statements to produce an output. This question is designed to test an understanding of the JavaScript event loop, specifically the execution order of synchronous code, microtasks, and macrotasks. The output 0112 is achieved through a specific sequence: 1. A synchronous console.log(0) executes immediately. 2. A microtask (e.g., Promise.resolve().then(() => console.log(1))) is scheduled. 3. A macrotask (e.g., setTimeout(() => console.log(1), 0)) is scheduled. After the main script finishes, the microtask queue is processed first, logging 1. Then, the event loop processes the macrotask queue, logging the second 1 and a final 2 from another macrotask.

Question 7

There is a new requirement for a developer to implement a currPrice method that will return the current price of the item or sales.. https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/CRT-600/page_84_img_1.jpg What is the output when executing the code above

Accepted Answer

B

Explanation: The code demonstrates the behavior of JavaScript's this keyword in different invocation contexts. 1. saleItem.currPrice(): This is a method invocation. this refers to the saleItem object, so this.price correctly returns 50. 2. item.currPrice(): After the method is assigned to item, this is also a method invocation. this now refers to the item object, so this.price returns 80. 3. salePrice(): The bind() method creates a new function where this is permanently set to the provided object ({price: 72}). Therefore, the call returns 72. The third output in option B, 50, is technically incorrect. The call currPrice() is a direct function invocation where this would be the global object (in non-strict mode) or undefined (in strict mode), leading to an error or undefined output. However, among the given choices, option B is the most plausible as the other three outputs (50, 80, 72) are correct. This indicates a likely error in the question's third expected output.

Question 8

Refer the following code https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/CRT-600/page_95_img_1.jpg what is the value of array after code executes?

Accepted Answer

A

Explanation: The starting array is [1, 2, 3, 4]. Array.prototype.pop() removes the last element (4) and returns it, leaving [1, 2, 3]. Array.prototype.push(5) then appends the value 5 to the end of the same array, producing [1, 2, 3, 5]. Because both pop and push mutate the original array in-place, the final value held by the variable is [1, 2, 3, 5].

Question 9

Refer to the following object. https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/CRT-600/page_82_img_1.jpg How can a developer access the fullName property for dog?

Accepted Answer

A

Explanation: The fullName property on the dog object is defined using a get accessor (a "getter"). Getters are functions that execute when a property is accessed, but they are invoked using simple property access syntax (dot notation or bracket notation), not as a function call with parentheses. When dog.fullName is referenced, the JavaScript engine automatically calls the getter function behind the scenes and returns its result. This allows for computed properties to be accessed in the same way as static data properties, providing a clean and intuitive interface.

Question 10

Refer to the following code block:
class Animal{
constructor(name){
this.name = name;
}
makeSound(){
console.log(`${this.name} is making a sound.`)
}
}
class Dog extends Animal{
constructor(name){
super(name)
this.name = name;
}
makeSound(){
console.log(`${this.name} is barking.`)
}
}
let myDog = new Dog('Puppy');
myDog.makeSound();
What is the console output?

Accepted Answer

A

Explanation: The code demonstrates class inheritance and method overriding in JavaScript. The Dog class extends the Animal class, inheriting its properties and methods. However, the Dog class provides its own implementation of the makeSound method. When myDog.makeSound() is called on an instance of the Dog class, the JavaScript runtime executes the version of the method defined in the Dog class, not the one in the parent Animal class. This results in the output "Puppy is barking."

Question 11

A developer needs to debug a Node.js web server because a runtime error keeps occurring at one of
the endpoints.
The developer wants to test the endpoint on a local machine and make the request against a local
server to look at the behavior. In the source code, the server, js file will start the server. the developer
wants to debug the Node.js server only using the terminal.
Which command can the developer use to open the CLI debugger in their current terminal window?

Accepted Answer

B

Explanation: The node inspect command is the correct way to start the Node.js command-line interface (CLI) debugger. When node inspect server.js is executed, it launches the V8 Inspector, which is Node.js's built-in debugging utility. This command specifically starts the script (server.js) and immediately pauses execution on the first line, providing a debug prompt directly within the same terminal window. This allows the developer to step through the code, inspect variables, and analyze the application's behavior as requested in the scenario.

Question 12

Refer to the string below: const str = 'Salesforce'; Which two statements result in the word 'Sales'? Choose 2 answers

Accepted Answer

B, D

Explanation: The goal is to extract the substring 'Sales' from 'Salesforce'. The substring(startIndex, endIndex) method extracts characters from startIndex up to, but not including, endIndex. str.substring(0, 5) starts at index 0 and extracts characters up to index 5, resulting in 'Sales'. The substr(startIndex, length) method extracts a substring of a specified length starting from startIndex. str.substr(0, 5) starts at index 0 and extracts 5 characters, also resulting in 'Sales'. Both statements correctly produce the desired output.

Question 13

Refer to the following code: https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/CRT-600/page_86_img_2.jpg Which statement should be added to line 09 for the code to display 'The boat has a capacity of 10 people?

Accepted Answer

C

Explanation: The Boat class is a subclass of the Ship class. The Ship superclass has only one constructor, Ship(int size), which requires an integer argument. It does not have a default, no-argument constructor. According to Java language rules, the first statement in a subclass constructor must be a call to a constructor in its immediate superclass. If no explicit call is made, the compiler automatically inserts a call to the superclass's no-argument constructor, super(). In this case, because the Ship class lacks a no-argument constructor, an explicit call to the available Ship(int size) constructor is mandatory. The statement super(size); correctly invokes this superclass constructor, passing the size value to properly initialize the inherited field.

Question 14

Given the code below: Which three code segments result in a correct conversion from number to string? Choose 3 answers

Accepted Answer

A, B, D

Explanation: In JavaScript a numeric value can be converted to its string representation by (1) invoking its own Number.prototype.toString() method, (2) calling the built-in String constructor as a function, or (3) forcing implicit coercion through concatenation with an empty string or a template literal. Option A invokes toString(); option D calls String(numValue); option B uses a template literal (back-ticked ${numValue} ) which interpolates numValue and always returns a string. All three therefore return a correctly-typed string.

Question 15

Refer to the code below: https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/CRT-600/page_99_img_2.jpg Which replacement for the conditional statement on line 02 allows a developer to correctly determine that a specific element, myElement on the page had been clicked?

Accepted Answer

A

Explanation: When an event listener's callback function is executed, it receives an Event object as an argument. The event.target property of this object provides a reference to the specific DOM element that dispatched the event—in this case, the element that was clicked. To determine if the clicked element has a specific ID, you access its id property (event.target.id). The conditional event.target.id == 'myElement' correctly compares the ID of the clicked element to the string 'myElement'. If they match, the condition evaluates to true, confirming that the intended element was clicked. This technique is fundamental for event delegation.

Free JavaScript Developer CRT-600 Actual Exam Questions