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| Section | Weight | Objectives |
|---|---|---|
| Topic 1: Objects, Functions, and Classes | 25% | - Closures and execution context - Class syntax, inheritance, and prototypes - Modules and imports/exports - Function definitions, parameters, and scope - Decorators and advanced function patterns - Object creation, properties, and methods |
| Topic 2: Variables, Types, and Collections | 23% | - Array methods and data manipulation - Type coercion and conversion rules - Truthy and falsy values - Working with strings, numbers, dates, and booleans - JSON parsing and usage - Variable declaration and initialization |
| Topic 3: Debugging and Error Handling | 7% | - Error types and exception handling - Console methods and logging - Debugging tools and breakpoints - Defensive programming practices |
| Topic 4: Testing | 7% | - Test doubles and mocks - Code coverage and best practices - Unit testing concepts - Testing frameworks and assertions |
| Topic 5: Server-Side JavaScript | 8% | - Command-line tools and scripts - Node.js fundamentals and runtime - Core Node.js modules - Module system and require/import |
| Topic 6: Browsers and Events | 17% | - Event handling, propagation, and delegation - Document Object Model (DOM) manipulation - Window and document object properties - Browser APIs and Web Storage - Script loading and execution order |
| Topic 7: Asynchronous Programming | 13% | - Event loop and micro/macro tasks - Fetch API and HTTP requests - Async/await syntax - Promises and chaining - Callbacks and callback hell |
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NEW QUESTION # 90
Refer to the following code (correcting the missing template literal backticks):
let codeName = ' Bond ' ;
let sampleText = `The name is ${codeName}, Jim ${codeName}`;
A developer is trying to determine if a certain substring is part of a string.
Which three code statements return true?
Answer: B,C,D
Explanation:
First, compute sampleText:
let codeName = ' Bond ' ;
let sampleText = `The name is ${codeName}, Jim ${codeName}`;
The template literal evaluates to:
" The name is Bond, Jim Bond "
Now evaluate each statement:
Option A: sampleText.includes( ' Jim ' );
* String.prototype.includes(substring) returns true if substring occurs anywhere in the string.
* sampleText clearly contains " Jim " ( " The name is Bond, Jim Bond " ).
* So this returns true.
Option B: sampleText.includes( ' The ' , 1);
* includes(searchString, position) starts searching from the given position index.
* " The name is Bond, Jim Bond " has " The " starting at index 0.
* Starting search at index 1 means " The " at index 0 is not considered, and there is no second " The " .
* So this returns false.
Option C: sampleText.includes( ' Jim ' , 4);
* " Jim " appears after " The name is Bond, " which is longer than 4 characters; the index of " Jim " is well past 4.
* So when searching from index 4, " Jim " is still found.
* This returns true.
Option D: sampleText.indexOf( ' Bond ' ) !== -1;
* String.prototype.indexOf(substring) returns:
* -1 if the substring is not found,
* Otherwise, the starting index of the first occurrence.
* " Bond " appears twice in " The name is Bond, Jim Bond " .
* So sampleText.indexOf( ' Bond ' ) is some non-negative index (for the first occurrence).
* Therefore indexOf( ' Bond ' ) !== -1 is true.
Option E: sampleText.substring( ' Jim ' );
* substring expects numeric indexes: substring(startIndex, endIndex?).
* If given a string " Jim " as the argument, JavaScript coerces it to a number:
* Number( ' Jim ' ) # NaN
* NaN for startIndex is treated as 0.
* So sampleText.substring( ' Jim ' ) is effectively sampleText.substring(0), which returns the full string " The name is Bond, Jim Bond " .
* This is a string , not a boolean. The question asks "which code statements return true?"
* This statement returns a string, not the boolean value true.
Thus, the three statements that actually return true (boolean) are:
The answer: A, C, D
Study Guide / Concept References (no links):
* Template literals and ${} interpolation
* String.prototype.includes(searchString, position?)
* String.prototype.indexOf(substring) and checking for !== -1
* String.prototype.substring(start, end?) and argument coercion
* Boolean vs non-boolean return types in string methods
NEW QUESTION # 91
Refer to the code below:
const searchText = ' Yay! Salesforce is amazing! ' ;
let result1 = searchText.search(/sales/i);
let result2 = searchText.search(/sales/);
console.log(result1);
console.log(result2);
After running this code, which result is displayed on the console?
Answer: C
Explanation:
String: " Yay! Salesforce is amazing! "
Index positions:
* ' Y ' at 0, ' a ' at 1, ' y ' at 2, ' ! ' at 3, space at 4, ' S ' at 5, ' a ' at 6, ' l ' at 7, ' e ' at 8, ' s ' at 9, etc.
Substring " Sales " starts at index 5.
String.prototype.search with a regex returns the index of the first match or -1 if there is no match.
* searchText.search(/sales/i);
* /sales/i is case-insensitive because of the i flag.
* It matches " Sales " beginning at index 5.
* So result1 is 5.
* searchText.search(/sales/);
* /sales/ is case-sensitive.
* It requires lowercase " sales " .
* The text has " Sales " with uppercase S, so this does not match.
* search returns -1 when there is no match.
* So result2 is -1.
Console output:
* First log: 5
* Second log: -1
Option D matches this.
Concepts: regex search, case sensitivity vs i flag, String.prototype.search return values.
NEW QUESTION # 92
Refer to the following code that performs a basis mathematical operation on a provided input:
How should line o2 be written to ensure that x evaluated to 6 in the line below?
Let x calculate (''g'');
Answer: D
NEW QUESTION # 93
There is a new requirement for a developer to implement a currPrice method that will return the current price of the item or sales..
What is the output when executing the code above
Answer: D
NEW QUESTION # 94
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?
Answer: C
NEW QUESTION # 95
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