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| Section | Weight | Objectives |
|---|---|---|
| Topic 1: Browser and Events | 17% | - Event propagation (bubbling and capturing) - Interacting with forms and user input - Browser-specific APIs - DOM manipulation - Browser Developer Tools usage - Event handling and listeners |
| Topic 2: Variables, Types, and Collections | 23% | - Truthy and falsy evaluations - Primitive and complex data types - Type coercion and conversion - Variable declarations and initialization - Arrays and collections - Strings, numbers, and dates - JSON parsing and manipulation |
| Topic 3: Testing | 7% | - Test coverage and reliability - Unit testing concepts - Test effectiveness evaluation - Writing and modifying unit tests |
| Topic 4: Asynchronous Programming | 13% | - Async/Await syntax - Asynchronous patterns for business requirements - Callbacks - Promises (creation, chaining, error handling) - Event loop and execution flow |
| Topic 5: Objects, Functions, and Classes | 25% | - ES6 classes and inheritance - Variable scope and closures - Modules and decorators - Function declarations and expressions - Object creation and manipulation - Higher-order functions - Prototypal inheritance - Arrow functions - Execution flow and context |
| Topic 6: Debugging and Error Handling | 7% | - Console methods for debugging - Breakpoints and code inspection - Custom error types - Error handling techniques (try/catch/finally) |
| Topic 7: Server Side JavaScript | 8% | - CLI commands - Node.js fundamentals - Core Node.js modules - Package management (npm) - Server-side JavaScript implementations |
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NEW QUESTION # 61
Refer to the code below:
function changeValue(param) {
Param =5;
}
Let a =10;
Let b =5;
changeValue(b);
Const result = a+ " - "+ b;
What is the value of result when code executes?
Answer: B
NEW QUESTION # 62
Refer to the code below:
for(let number =2 ; number <= 5 ; number += 1 ) {
// insert code statement here
}
The developer needs to insert a code statement in the location shown. The code
statement has these requirements:
1. Does require an import
2. Logs an error when the boolean statement evaluates to false
3. Works in both the browser and Node.js
Which meet the requirements?
Answer: D
NEW QUESTION # 63
A developer wants to use a module called DatePrettyPrint.
This module exports one default function called printDate().
How can the developer import and use printDate()?
Answer: C
Explanation:
ES Modules follow these rules:
* Default exports are imported using:
* import anyName from ' module '
The name chosen in the import does NOT need to match the exported name.
* If a module exports:
* export default function printDate() {}
then consuming code should import the function directly:
import printDate from ' /path/DatePrettyPrint.js ' ;
* To execute it:
* printDate();
Option analysis:
* A incorrect: import DatePrettyPrint() is invalid syntax. Also calling printDate() without importing it is incorrect.
* B incorrect: A default export imported as DatePrettyPrint gives the function itself, not an object containing methods. You cannot call DatePrettyPrint.printDate().
* C incorrect: Imports printDate but then calls DatePrettyPrint.printDate(), which does not exist.
* D correct: Correct import of a default-exported function. Correct direct invocation.
JavaScript Knowledge References (text-only)
* Default export # imported without braces.
* Importing default functions gives a callable function, not an object.
* Correct syntax: import identifier from " module " .
NEW QUESTION # 64
Refer to the following array:
Let arr = [1, 2, 3, 4, 5];
Which three options result in x evaluating as [1,2]?
Choose 3 answer
Answer: A,B,D
NEW QUESTION # 65
Refer to the code below:
let inArray = [ [1, 2], [3, 4, 5] ];
Which two statements result in the array [1, 2, 3, 4, 5]?
(With corrected typing errors: usArray # inArray, .. # ....)
Answer: B,C
Explanation:
We start with the array:
let inArray = [ [1, 2], [3, 4, 5] ];
This is an array of two inner arrays:
* First element: [1, 2]
* Second element: [3, 4, 5]
The desired result is to transform this into a single, flat array:
[1, 2, 3, 4, 5]
This is accomplished by using Array.prototype.concat to concatenate the inner arrays into one new array, optionally combined with the spread syntax (...) or Function.prototype.apply.
* Option A: [].concat(...inArray);
Relevant concepts:
* Spread syntax (...inArray) expands an iterable into separate arguments.
* Array.prototype.concat joins arrays or values into a new array. When you pass arrays as arguments to concat, it flattens them one level into the result.
Step-by-step behavior:
* inArray is [ [1, 2], [3, 4, 5] ].
* ...inArray expands into [1, 2] and [3, 4, 5] as separate arguments.
* So [].concat(...inArray) is equivalent to:
* [].concat([1, 2] , [3, 4, 5]);
* concat processes each argument:
* For [1, 2], it adds 1 and 2 into the result array.
* For [3, 4, 5], it adds 3, 4, and 5 into the result array.
The final outcome is:
[1, 2, 3, 4, 5]
Therefore, Option A correctly produces the desired array.
* Option B: [].concat.apply(inArray, [] );
Corrected name from usArray to inArray.
Relevant concepts:
* Function.prototype.apply(fnThis, argsArray) invokes a function with a specific this value and a list of arguments passed as an array.
Here:
* thisArg is inArray.
* argsArray is [] (no actual arguments passed).
So the call:
[].concat.apply(inArray, [] );
is equivalent to:
Array.prototype.concat.apply(inArray, []);
// i.e. inArray.concat();
Since there are no extra arguments, inArray.concat() simply returns a shallow copy of inArray:
[ [1, 2], [3, 4, 5] ]
This remains an array of arrays and is not flattened into [1, 2, 3, 4, 5]. Therefore, Option B does not produce the required result.
* Option C: [].concat::...inArray();
Corrected name from usArray to inArray and .. to ....
This expression uses syntax that is not part of standard JavaScript:
* :: (double colon) was proposed in early drafts as a bind operator but is not part of the official ECMAScript standard.
* The combination concat::...inArray() is invalid in normal JavaScript engines and cannot be used as a valid way to flatten arrays.
* In addition, inArray() would imply calling inArray as a function, but it is an array, which would cause a runtime error.
Hence, Option C is syntactically or semantically invalid in standard JavaScript and does not provide the required result [1, 2, 3, 4, 5].
* Option D: [].concat.apply({}, inArray);
Corrected name from usArray to inArray.
Relevant concepts:
* Again, Function.prototype.apply is used to call concat with a specific this value and arguments provided as an array.
* concat treats its this value as an array-like object but ultimately returns a new array containing concatenated elements.
In this expression:
[].concat.apply({}, inArray);
* thisArg is {} (an empty object).
* argsArray is inArray, which is [ [1, 2], [3, 4, 5] ].
Using apply, this is interpreted as calling concat like:
Array.prototype.concat.call({}, [1, 2], [3, 4, 5] );
concat then:
* Starts from the array-like this (here {} is treated as an empty base).
* Takes the first argument [1, 2] and appends its elements 1 and 2 to the result.
* Takes the second argument [3, 4, 5] and appends its elements 3, 4, and 5 to the result.
The resulting new array is:
[1, 2, 3, 4, 5]
Therefore, Option D also correctly produces the required array.
* Final evaluation of all options:
* Option A: Uses spread syntax with concat and correctly flattens one level: [1, 2, 3, 4, 5].
* Option B: Equivalent to inArray.concat(), leaving it as [[1, 2], [3, 4, 5]] . Does not flatten the structure.
* Option C: Uses non-standard and invalid syntax; not a valid or correct JavaScript solution.
* Option D: Uses apply with concat, passing the inner arrays as arguments and flattening one level to [1,
2, 3, 4, 5].
Thus, the two correct statements are:
The answer: A, D
References of JavaScript knowledge documents or Study Guide (concept names only):
* Array.prototype.concat (concatenating and one-level flattening behavior)
* Spread syntax for arrays (...array)
* Function.prototype.apply (calling a function with a given this value and arguments list)
* Array flattening by one level using concat with array arguments
* Distinction between nested arrays and flat arrays in JavaScript
NEW QUESTION # 66
......
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