Free Salesforce-JavaScript-Developer Practice Test Questions (2026)

Given the following code:
Let x =null;
console.log(typeof x);
What is the output of the line 02?

A. “Null”

B. “X”

C. “Object”

D. “undefined”

A developer wants to use a try...catch statement to catch any error that countSheep () may throw and pass it to a handleError () function.
What is the correct implementation of the try...catch?

A. setTimeout(function() {
try {
countSheep();
} catch (e) {
handleError(e);
}
}, 1000);

B. try {
countSheep();
} finally {
handleError(e);
}

C. try {
countSheep();
} handleError (e){
catch(e);
}

D. try {
setTimeout(function() {
countSheep();
}, 1000);
} catch (e) {
handleError(e);
}

A team that works on a big project uses npm to deal with projects dependencies.
A developer added a dependency does not get downloaded when they execute npm install.
Which two reasons could be possible explanations for this?
Choose 2 answers

A. The developer missed the option --add when adding the dependency.

B. The developer added the dependency as a dev dependency, and NODE_ENV Is set to production.

C. The developer missed the option --save when adding the dependency.

D. The developer added the dependency as a dev dependency, and
NODE_ENV is set to production.

Refer to the HTML below:

Leo
Tony
Tiger


Which JavaScript statement results in changing “ Tony” to “Mr. T.”?

A. document.querySelectorAll(‘$main $TONY’).innerHTML = ’ Mr. T. ’;

B. document.querySelector(‘$main li:second-child’).innerHTML = ’ Mr. T. ’;

C. document.querySelector(‘$main li.Tony’).innerHTML = ’ Mr. T. ’;

D. document.querySelector(‘$main li:nth-child(2)’),innerHTML = ’ Mr. T. ’;

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

B. > 5 > -1

C. > 5 > 0

Refer to code below:
Const objBook = {
Title: ‘Javascript’,
};
Object.preventExtensions(objBook);
Const newObjBook = objBook;
newObjectBook.author = ‘Robert’;
What are the values of objBook and newObjBook respectively ?

A. [title: “javaScript”] [title: “javaScript”]

B. {author: “Robert”, title: “javaScript}
Undefined

C. {author: “Robert”, title: “javaScript}
{author: “Robert”, title: “javaScript}

D. {author: “Robert”}
{author: “Robert”, title: “javaScript}

A developer wants to define a function log to be used a few times on a single-file
JavaScript script.
01 // Line 1 replacement
02 console.log('"LOG:', logInput);
03 }
Which two options can correctly replace line 01 and declare the function for use?
Choose 2 answers

A. function leg(logInput) {

B. const log(loginInput) {

C. const log = (logInput) => {

D. function log = (logInput) {

Refer to the code below:
Function changeValue(obj) {
Obj.value = obj.value/2;
}
Const objA = (value: 10);
Const objB = objA;
changeValue(objB);
Const result = objA.value;
What is the value of result after the code executes?

A. 10

B. Nan

C. 5

D. Undefined

developer uses the code below to format a date.

let timerId = setTimeout (timedFunction, 1000);
Which statement allows a developer to cancel the scheduled timed function?

A. A. removeTimeout(timedFunction);

B. removeTimeout(timerId);

C. clearTimeout(timerId);

D. clearTimeout(timedFunction);

let timerId = setTimeout (timedFunction, 1000);
Which statement allows a developer to cancel the scheduled timed function?

A. removeTimeout(timedFunction);

B. removeTimeout(timerId);

C. clearTimeout(timerId);

D. clearTimeout(timedFunction);