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| Section | Weight | Objectives |
|---|---|---|
| Asynchronous Programming | 13% | - Event loop and asynchronous code execution - Promises and async/await - Callback patterns |
| Testing | 7% | - Test-driven development principles - Automated testing strategies - Unit testing with Jest |
| Objects, Functions, and Classes | 25% | - JavaScript modules (export, import) - ES6 Classes, constructors, methods, and inheritance - Higher-order functions and closures - Function declarations, expressions, and arrow functions - Object creation, properties, and prototypal inheritance |
| Variables, Types, and Collections | 23% | - Type coercion and type conversion - Array manipulation (map, filter, reduce, forEach, find) - Variable declaration (var, let, const, scoping, hoisting) - JSON parsing and stringification - String manipulation and Date objects |
| Server Side JavaScript | 8% | - Salesforce API integration - Modules and file operations - Node.js applications |
| Debugging and Error Handling | 7% | - try-catch blocks - Logging strategies and debugging techniques |
| Browser and Events | 17% | - Event handling, propagation, bubbling, and capturing - DOM manipulation - Browser Developer Tools |
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NEW QUESTION # 132
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?
Answer: A,D
NEW QUESTION # 133
A developer has a fizzbuzz function that, when passed in a number, returns the following:
'fizz' if the number is divisible by 3.
'buzz' if the number is divisible by 5.
'fizzbuzz' if the number is divisible by both 3 and 5.
Empty string '' if the number is divisible by neither 3 nor 5.
Which two test cases properly test scenarios for the fizzbuzz function?
Answer: A,C
Explanation:
Comprehensive and Detailed Explanation From Exact Extract JavaScript knowledge:
First, recall the fizzbuzz rules:
If n divisible by 3 and not by 5 → return 'fizz'.
If n divisible by 5 and not by 3 → return 'buzz'.
If n divisible by both 3 and 5 → return 'fizzbuzz'.
Otherwise → return '' (empty string).
Evaluate each test:
Option A:
let res = fizzbuzz(true);
console.assert(res === '');
In JavaScript, when using arithmetic operations with true, it is coerced to the number 1. A typical implementation of fizzbuzz would treat the argument as a number and compute:
true % 3 → 1 % 3 → 1
true % 5 → 1 % 5 → 1
So true is effectively treated as 1, which is divisible by neither 3 nor 5. The function should return ''. The assertion res === '' will pass.
This test covers the scenario "neither divisible by 3 nor 5".
Option B:
let res = fizzbuzz(3);
console.assert(res === '');
3 is divisible by 3 but not by 5.
According to fizzbuzz rules, fizzbuzz(3) should return 'fizz'.
This test expects '', so it is incorrect; the assertion would fail in a correct implementation.
Option C:
let res = fizzbuzz(5);
console.assert(res === 'fizz');
5 is divisible by 5 but not by 3.
According to fizzbuzz rules, fizzbuzz(5) should return 'buzz'.
This test expects 'fizz', so it is incorrect.
Option D:
let res = fizzbuzz(15);
console.assert(res === 'fizzbuzz');
15 is divisible by both 3 and 5.
According to fizzbuzz rules, fizzbuzz(15) should return 'fizzbuzz'.
This assertion correctly matches the expected result, so it is a proper test case.
Thus, the two test cases that correctly test valid fizzbuzz behavior are:
Study Guide / Concept Reference (no links):
Modulo operator (%) for divisibility checks
Truthy/number coercion of boolean true in arithmetic (Number(true) === 1) Designing unit tests with console.assert Typical fizzbuzz logic structure and expected outputs
________________________________________
NEW QUESTION # 134
Considering type coercion, what does the following expression evaluate to?
True + '13' + NaN
Answer: C
NEW QUESTION # 135
Refer to the code:
01 console.log('Start');
02 Promise.resolve('Success').then(function(value) {
03 console.log('Success');
04 });
05 console.log('End');
What is the output after the code executes successfully?
Answer: D
Explanation:
console.log('Start') runs immediately (synchronous).
Promise.resolve().then(...) places the callback in the microtask queue. The .then handler does not run immediately.
console.log('End') runs next (still synchronous).
After the synchronous script finishes, the microtask queue runs, logging "Success".
Execution order:
Start
End
Success
This matches option B.
JavaScript Knowledge Reference (text-only)
Promise .then() callbacks execute after the current call stack finishes (microtask queue).
Synchronous logs run immediately, before promise callbacks.
NEW QUESTION # 136
Which statement allows a developer to update the browser navigation history without a page refresh?
Answer: C
Explanation:
The correct answer is C.
The browser provides the History API through:
window.history
To add a new entry to the browser's session history without refreshing the page, JavaScript uses:
window.history.pushState(state, title, url);
So the valid statement is:
window.history.pushState(newStateObject, '', null);
This updates the browser history stack without forcing a full page reload. It is commonly used in single-page applications when changing views or routes dynamically.
The method accepts three arguments:
window.history.pushState(stateObject, title, url);
stateObject stores custom data associated with the history entry.
title is usually passed as an empty string because many browsers ignore it.
url optionally changes the displayed URL. Passing null means no new URL is provided.
Option A is incorrect because:
window.customHistory
is not the standard browser History API object.
Option B is incorrect because:
createState()
is not a valid History API method.
Option D is incorrect because:
updateState()
is not a valid History API method.
The correct browser API method is:
window.history.pushState()
Therefore, the verified answer is C.
NEW QUESTION # 137
......
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