JavaScript-Developer-I Exam - JavaScript-Developer-I Zertifikatsfragen

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Salesforce JavaScript-Developer-I Exam Syllabus Topics:

Section	Weight	Objectives
Topic 1: Objects, Functions, and Classes	25%	- Variable scope and closures - Object creation and manipulation - Prototypal inheritance - Higher-order functions - ES6 classes and inheritance - Modules and decorators - Execution flow and context - Function declarations and expressions - Arrow functions
Topic 2: Server Side JavaScript	8%	- Node.js fundamentals - Server-side JavaScript implementations - CLI commands - Core Node.js modules - Package management (npm)
Topic 3: Debugging and Error Handling	7%	- Breakpoints and code inspection - Custom error types - Error handling techniques (try/catch/finally) - Console methods for debugging
Topic 4: Browser and Events	17%	- Interacting with forms and user input - Browser Developer Tools usage - DOM manipulation - Event handling and listeners - Browser-specific APIs - Event propagation (bubbling and capturing)
Topic 5: Testing	7%	- Writing and modifying unit tests - Test effectiveness evaluation - Unit testing concepts - Test coverage and reliability
Topic 6: Asynchronous Programming	13%	- Promises (creation, chaining, error handling) - Event loop and execution flow - Callbacks - Async/Await syntax - Asynchronous patterns for business requirements
Topic 7: Variables, Types, and Collections	23%	- Strings, numbers, and dates - JSON parsing and manipulation - Variable declarations and initialization - Primitive and complex data types - Type coercion and conversion - Arrays and collections - Truthy and falsy evaluations

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Salesforce JavaScript-Developer-I Zertifikatsfragen & JavaScript-Developer-I Prüfungsfragen

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Salesforce Certified JavaScript Developer (JS-Dev-101) JavaScript-Developer-I Prüfungsfragen mit Lösungen (Q63-Q68):

63. Frage
Refer to the code below:
01 const myFunction = arr = > {
02 return arr.reduce((result, current) = > {
03 return result + current;
04 }, 10);
05 }
What is the output of this function when called with an empty array?

A. Returns 5 # (Text here appears to be a typo; correct value is 10, see explanation.)
B. Throws an error
C. Returns 0
D. Returns NaN

Antwort: A

Begründung:
We call:
myFunction([]);
Inside:
arr.reduce((result, current) = > {
return result + current;
}, 10);
Key points about Array.prototype.reduce:
* Signature: array.reduce(callback, initialValue)
* If initialValue is provided and the array is empty , reduce:
* Does not call the callback at all.
* Simply returns initialValue.
Here:
* arr is [] (empty).
* initialValue is 10.
So:
* No iterations of the callback happen (no elements to process).
* The return value is the initial value: 10.
So the actual output is:
myFunction([]) === 10;
Among the options:
* A: 0 - incorrect, because the initial value is 10, not 0.
* B: Throws an error - reduce throws only if the array is empty and there is no initialValue. Here we have an initial value, so no error.
* C: NaN - there is no arithmetic with undefined or invalid values; we just return 10.
* D: Returns 5 - the numeric value given is wrong; the correct value is 10.
Given the logic, the correct conceptual result is 10 . The option text "Returns 5" is almost certainly a typo for "Returns 10". Since the letter that is intended to represent the correct behavior is D, we keep:
The answer: D
Study Guide / Concept References (no links):
* Array.prototype.reduce behavior with initialValue
* Behavior of reduce on an empty array with and without initialValue
* Return value when no iterations run

64. Frage
A developer at Universal Containers is creating their new landing page basedon HTML, CSS, and JavaScript.
To ensure that visitors have a good experience, a script named personalizeWebsiteContent needs to be executed when the webpage is fully loaded (HTML content and all related files), in order to do some custom initializations.
Which implementation should be used to call Fe:s:-a;::eHec5;te::.-.ter.: based on the business requirement above?

A. Add a handler to the personalizeWebsiteContent script to handlethe load event
B. Add a listener to thewindow object to handle the DOMContentLoaded event
C. Add a listener to the window object to handle the lead event
D. Add a handler to the personalizeWebsiteContent script tohandle the DOMContentLoaded event

Antwort: C

65. Frage
Which javascript methods can be used to serialize an object into a string and deserialize a JSON string into an object, respectively?

A. JSON.stringify and JSON.parse
B. JSON.encode and JSON.decode
C. JSON.serialize and JSON.deserialize
D. JSON.parse and JSON.deserialize

Antwort: A

66. Frage
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?

A. true
false
B. 5
undefined
C. 5
0
D. 5
-1

Antwort: D

Begründung:
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.

67. Frage
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()?

A. import DatePrettyPrint() from ' /path/DatePrettyPrint.js ' ;
printDate();
B. import printDate from ' /path/DatePrettyPrint.js ' ;
printDate();
C. import DatePrettyPrint from ' /path/DatePrettyPrint.js ' ;
DatePrettyPrint.printDate();
D. import printDate from ' /path/DatePrettyPrint.js ' ;
DatePrettyPrint.printDate();

Antwort: B

Begründung:
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 " .

68. Frage
......

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JavaScript-Developer-I Zertifikatsfragen: https://www.pruefungfrage.de/JavaScript-Developer-I-dumps-deutsch.html

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