Reliable Salesforce Developer JavaScript-Developer-I Dumps PDF Sep 01, 2026 Recently Updated Questions
Pass Your Salesforce JavaScript-Developer-I Exam with Correct 149 Questions and Answers
NEW QUESTION # 16
developer removes the HTML class attribute from the checkout button, so now it is simply:
<button>Checkout</button>.
There is a test to verify the existence of the checkout button, however it looks for a button with class= "blue". The test fails because no such button is found.
Which type of test category describes this test?
- A. False positive
- B. True negative
- C. True positive
- D. False negative
Answer: D
NEW QUESTION # 17
Which three statements are true about promises ?
Choose 3 answers
- A. The executor of a new Promise runs automatically.
- B. A Promise has a .then() method.
- C. A settled promise can become resolved.
- D. A pending promise can become fulfilled, settled, or rejected.
- E. A fulfilled or rejected promise will not change states .
Answer: B,D,E
NEW QUESTION # 18
Which function should a developer use to repeatedly execute code at a fixed time interval?
- A. setPeriod
- B. setInterval
- C. setTimeout
- D. setInterim
Answer: B
NEW QUESTION # 19
A developer has code that calculates a restaurant bill, but generates incorrect answers while testing the code.
Which option allows the developer to step into each function execution within calculateBill?
- A. Using the debugger command on line 05.
- B. Calling the console. Trace( total ) method on line 03.
- C. Wrapping findsubtotal in a console .log method.
- D. Using the debugger command on line 03.
Answer: D
NEW QUESTION # 20
Refer to the code below:
What is display when the cod executes?
- A. Undefined
- B. null
- C. A
- D. ReferenceError: b is not defined
Answer: C
NEW QUESTION # 21
Which two code snippets show working examples of a recursive function?
Choose 2 answers
- A. Function factorial ( numVar ) {
If (numVar < 0) return;
If ( numVar === 0 ) return 1;
return numVar -1; - B. Const factorial =numVar => {
If (numVar < 0) return;
If ( numVar === 0 ) return 1;
return numVar * factorial ( numVar - 1 );
}; - C. Let countingDown = function(startNumber) {
If ( startNumber >0) {
console.log(startNumber) ;
return countingDown(startNUmber);
} else {
return startNumber;
}}; - D. Const sumToTen = numVar => {
If (numVar < 0)
Return;
return sumToTen(numVar + 1)};
Answer: B,C
NEW QUESTION # 22
Given the following code:
01 let x = null;
02 console.log(typeof x);
What is the output of line 02?
- A. " null "
- B. " x "
- C. " undefined "
- D. " object "
Answer: D
Explanation:
This question focuses on the typeof operator and how JavaScript represents the type of the value null.
* Declaration on line 1:
let x = null;
Here:
* x is explicitly assigned the value null.
* In JavaScript, null is a special primitive value that represents "no value" or "empty value".
* Line 2:
console.log(typeof x);
The typeof operator returns a string indicating the type of the operand. For example:
* typeof 1 returns " number "
* typeof " hello " returns " string "
* typeof true returns " boolean "
* typeof undefined returns " undefined "
* typeof {} returns " object "
* typeof [] returns " object " (arrays are objects)
* typeof function() {} returns " function "
For null, due to an early design decision in JavaScript, the result is:
typeof null === " object "
This is a known historical quirk of the language:
* Although null is a primitive and conceptually means "no object", typeof null returns the string " object "
.
Therefore, typeof x when x is null evaluates to " object " .
So on line 2, the value printed is:
" object "
This matches option A.
The incorrect options are:
* B. " undefined " : would be typeof x if x were undefined, not null.
* C. " x " : typeof returns a string describing the type of the value, not the variable name.
* D. " null " : although intuitive, JavaScript does not return " null " for typeof null; it returns " object " instead.
Therefore, the correct answer is:
The answer: A
JavaScript knowledge / study guide reference concepts:
* typeof operator and its return values
* Primitive types in JavaScript (null, undefined, number, string, boolean, symbol, bigint)
* Historical behavior: typeof null returning " object "
* Difference between null and undefined in JavaScript
NEW QUESTION # 23
A developer has the following array of student test grades:
Let arr = [ 7, 8, 5, 8, 9 ];
The Teacher wants to double each score and then see an array of the students
who scored more than 15 points.
How should the developer implement the request?
- A. Let arr1 = arr.filter(( val) => ( return val > 15 )) .map (( num) => ( return num *2 ))
- B. Let arr1 = arr.mapBy (( num) => ( return num *2 )) .filterBy (( val ) => return val > 15 )) ;
- C. Let arr1 = arr.map((num) => num*2). Filter (( val) => val > 15);
- D. Let arr1 = arr.map((num) => ( num *2)).filterBy((val) => ( val >15 ));
Answer: C
NEW QUESTION # 24
01 function changeValue(obj) {
02 obj.value = obj.value / 2;
03 }
04 const objA = {value: 10};
05 const objB = objA;
06
07 changeValue(objB);
08 const result = objA.value;
What is the value of result after the code executes?
- A. 0
- B. undefined
- C. 1
- D. low
Answer: A
Explanation:
* objA is { value: 10 }.
* objB = objA; # both variables reference the same object .
* changeValue(objB);:
obj.value = obj.value / 2; // modifies the shared object
So:
* objA.value becomes 10 / 2 = 5.
Thus result is 5.
NEW QUESTION # 25
Refer to the code below:
Const searchTest = 'Yay! Salesforce is amazing!" ;
Let result1 = searchText.search(/sales/i);
Let result 21 = searchText.search(/sales/i);
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
Answer: B
NEW QUESTION # 26
Refer to the code snippet below:
Let array = [1, 2, 3, 4, 4, 5, 4, 4];
For (let i =0; i < array.length; i++)
if (array[i] === 4) {
array.splice(i, 1);
}
}
What is the value of array after the code executes?
- A. [1, 2, 3, 4, 4, 5, 4]
- B. [1, 2, 3, 4, 5, 4]
- C. [1, 2, 3, 4, 5, 4, 4]
- D. [1, 2, 3, 5]
Answer: A
Explanation:
NEW QUESTION # 27
Refer to the following object:
How can a developer access the fullname property for cat?
- A. Cat.function.fullName
- B. Cat.fullName
- C. Cat.fullname ( )
- D. Cat,get,fullname
Answer: D
NEW QUESTION # 28
A developer receives a comment from the Tech lead that the code below gives an error.
Which line edit should be made to make this code run?
- A. 03 if (year == 2019) (
- B. 01 let monthname = 'July ';
- C. 02 let year = 2019 ;
- D. 02 const year = 2020;
Answer: D
NEW QUESTION # 29
A developer is setting up a new Node.js server with a client library that is built using events and callbacks.
The library:
* Will establish a web socket connection and handle receipt of messages to the server.
* Will be imported with require, and made available with a variable called ws.
* The developer also wants to add error logging if a connection fails.
Given this information, which code segment shows the correct way to set up a client with two events that listen at execution time?
- A. ws.on( ' connect ' , () = > {
console.log( ' Connected to client ' );
});
ws.on( ' error ' , (error) = > {
console.log( ' ERROR ' , error);
}); - B. ws.on( ' connect ' , () = > {
console.log( ' Connected to client ' );
});
ws.on( ' error ' , (error) = > {
console.log( ' ERROR ' , error);
}); - C. ws.connect(() = > {
console.log( ' Connected to client ' );
}).catch((error) = > {
console.log( ' ERROR ' , error);
}); - D. try {
ws.connect(() = > {
console.log( ' Connected to client ' );
});
} catch(error) {
console.log( ' ERROR ' , error);
}
Answer: A
Explanation:
The correct answer is B .
This question is about the event-driven programming model commonly used in Node.js. Many Node.js libraries expose an .on() method to register callback functions for specific events.
The correct pattern is:
ws.on( ' eventName ' , callbackFunction);
In this case, the developer needs to listen for two events:
' connect '
and:
' error '
The correct implementation is:
ws.on( ' connect ' , () = > {
console.log( ' Connected to client ' );
});
ws.on( ' error ' , (error) = > {
console.log( ' ERROR ' , error);
});
This registers one listener for successful connection and another listener for connection errors.
Why this works professionally:
ws.on( ' connect ' , callback) tells the library:
"When the connection event happens, execute this callback."
ws.on( ' error ' , callback) tells the library:
"When an error event happens, execute this callback and pass the error object into it." Option A is incorrect because .catch() is used with Promises. The question specifically says the client library is built using events and callbacks , not Promise chaining.
Option D is incorrect because try...catch only catches synchronous errors during the immediate execution of ws.connect(). It will not reliably catch asynchronous connection errors emitted later by the web socket client.
Option C is identical to option B in the provided question. Since the expected answer normally requires selecting one option, B is selected as the verified answer.
Therefore, the verified answer is B .
NEW QUESTION # 30
A developer creates a simple webpage with an input filed. When a user enters text In the input field and clicks the button, the actual value of the field must be displayed in the console.
Here is the HTML file content:
The developer wrote the JavaScript code below:
When the user clicks the button, the output is always ''hello''.
What needs to be done to make this code work as expected?
- A. Replace line 04 with button.addEventListener (''onclick'', function ( ) (
- B. Replace line 04 with const input = document. getElementByName ('input') ;
- C. Replace line 04 with button, addCallback (''click'', function ( ) (
- D. Replace line 04 with console.log (input, value);
Answer: D
NEW QUESTION # 31
Which code statement below correctly persists an objects inlocal Storage ?
- A. const setLocalStorage= ( jsObject) => {window.localStorage.setItem(jsObject);}
- B. const setLocalStorage = (storageKey, jsObject) => {window.localStorage.persist(storageKey, jsObject);}
- C. const setLocalStorage = (storageKey, jsObject) => {window.localStorage.setItem(storageKey, JSON.stringify(jsObject));}
- D. const setLocalStorage = ( jsObject) =>{window.localStorage.connectObject(jsObject));}
Answer: C
NEW QUESTION # 32
Refer to the code below
let inArray = [[1,2],[3,4,5]];
which two statements results in the array [1,2,3,4,5]?
choose 2 answer
- A. [ ].concat([...inArray])
- B. [ ].concat.apply([ ],inArray);
- C. [ ].concat.apply(inArray,[ ]);
- D. [ ].concat(...inArray);
Answer: B,D
NEW QUESTION # 33
A developer is trying to handle an error within a function.
Which code segment shows the correct approach to handle an error without propagating it elsewhere?
- A.
- B.
- C.
- D.
Answer: A
NEW QUESTION # 34
Which code statement correctly retrieves and return an object from localStorage?
A)
B)
C)
D)
- A. Option C
- B. Option B
- C. Option A
- D. Option D
Answer: D
NEW QUESTION # 35
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?
- A. console.debug(number % 2 === 0);
- B. console.assert(number % 2 === 0);
- C. console.error(number % 2 === 0);
- D. assert (number % 2 === 0);
Answer: C
NEW QUESTION # 36
Refer to the code below:
Which value can a developer expect when referencing country,capital,cityString?
- A. 'NaN'
- B. An error
- C. undefined
- D. 'London'
Answer: A
NEW QUESTION # 37
A developer wants to use a module named universalContainerLib and then call functions from it.
How should a developer import every function from the module and then call the functions foo and bar?
- A. import (foo,bar) from '/path/universalContainerLib.js''
foo ( ) ;
bar ( ) ; - B. import all from '/path/universalContainerLib.js''
universalContainersLib.foo( ) ;
universalContainersLib bar ( ) : - C. import - as lib from '/path/universalContainerLib.js''
lib.foo( ) ;
lib. bar ( ) ; - D. import + from '/path/universalContainerLib.js''
universalContainersLib.foo( ) ;
universalContainersLib bar ( ) :
Answer: C
NEW QUESTION # 38
Refer to the following code that imports a module named utils:
import (foo, bar) from '/path/Utils.js';
foo() ;
bar() ;
Which two implementations of Utils.js export foo and bar such that the code above runs without error?
Choose 2 answers
- A. // FooUtils.js and BarUtils.js exist
Import (foo) from '/path/FooUtils.js';
Import (boo) from ' /path/NarUtils.js'; - B. Export default class {
foo() { return 'foo' ; }
bar() { return 'bar' ; }
} - C. const foo = () => { return 'foo' ; }
const bar = () => { return 'bar' ; }
export { bar, foo } - D. const foo = () => { return 'foo';}
const bar = () => {return 'bar'; }
Export default foo, bar;
Answer: B,C
NEW QUESTION # 39
A developer wrote 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 or 5.
Which two test cases will properly test scenarios for the fizzbuzz function?
Choose 2 answers
- A. let res = fizzbuzz(3);
console.assert ( res === ' buzz ' ) - B. let res = fizzbuzz(Infinity);
console.assert ( res === ' ' ) - C. let res = fizzbuzz(15);
console.assert ( res === ' fizzbuzz ' ) - D. let res = fizzbuzz(5);
console.assert ( res === ' ' );
Answer: A,B,C
NEW QUESTION # 40
Universal Container (UC) notices that its application allows users to search for account makes a network request each time a key is pressed. This results in too many request for the server to handle.
O address this problem, UC decides to implement a deboune function on the search string change handler. Choose 3 answers
- A. Ensure that the network request has the property debounce set to true,
- B. If the there is an existing setTimeout and the search string changes, cancel the existing setTimeout using the persisted timeout replace it with a new setTimeout.
- C. Store the timeId of the setTimeout last enqueued by the search string change handler.
- D. If there is an existing settimeout and the search string changes, allow the existing setTimeout to finish, and do not enqueue a settimeout.
- E. When the search string changes, enqueue the request within a setTimeout.
Answer: A,B,E
NEW QUESTION # 41
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