Salesforce Certified JavaScript Developer (JS-Dev-101) - JavaScript-Developer-I Exam Practice Test
Question 1
Corrected code:
let obj = {
foo: 1,
bar: 2
};
let output = [];
for (let something in obj) {
output.push(something);
}
console.log(output);
What is the output of line 11?
let obj = {
foo: 1,
bar: 2
};
let output = [];
for (let something in obj) {
output.push(something);
}
console.log(output);
What is the output of line 11?
Correct Answer: C
Explanation: Only visible for Actualtests4sure members. You can sign-up / login (it's free).
Question 2
Refer to the code below:
01 < html lang= " en " >
02 < table onclick= " console.log( ' Table log ' ); " >
03 < tr id= " row1 " >
04 < td > Click me! < /td >
05 < /tr >
06 < /table >
07 < script >
08 function printMessage(event) {
09 console.log( ' Row log ' );
10 event.stopPropagation();
11 }
12
13 let elem = document.getElementById( ' row1 ' );
14 elem.addEventListener( ' click ' , printMessage, false);
15 < /script >
16 < /html >
Which code change should be done for the console to log the following when " Click me! " is clicked?
Row log
Table log
01 < html lang= " en " >
02 < table onclick= " console.log( ' Table log ' ); " >
03 < tr id= " row1 " >
04 < td > Click me! < /td >
05 < /tr >
06 < /table >
07 < script >
08 function printMessage(event) {
09 console.log( ' Row log ' );
10 event.stopPropagation();
11 }
12
13 let elem = document.getElementById( ' row1 ' );
14 elem.addEventListener( ' click ' , printMessage, false);
15 < /script >
16 < /html >
Which code change should be done for the console to log the following when " Click me! " is clicked?
Row log
Table log
Correct Answer: C
Explanation: Only visible for Actualtests4sure members. You can sign-up / login (it's free).
Question 3
Refer to the code below:
01 let timedFunction = () = > {
02 console.log( ' Timer called. ' );
03 };
04
05 let timerId = setInterval(timedFunction, 1000);
Which statement allows a developer to cancel the scheduled timed function?
01 let timedFunction = () = > {
02 console.log( ' Timer called. ' );
03 };
04
05 let timerId = setInterval(timedFunction, 1000);
Which statement allows a developer to cancel the scheduled timed function?
Correct Answer: D
Explanation: Only visible for Actualtests4sure members. You can sign-up / login (it's free).
Question 4
A developer is required to write a function that calculates the sum of elements in an array but is getting undefined every time the code is executed. The developer needs to find what is missing in the code below.
01 const sumFunction = arr = > {
02 return arr.reduce((result, current) = > {
03 //
04 result += current;
05 //
06 }, 10);
07 };
Which line replacement makes the code work as expected?
01 const sumFunction = arr = > {
02 return arr.reduce((result, current) = > {
03 //
04 result += current;
05 //
06 }, 10);
07 };
Which line replacement makes the code work as expected?
Correct Answer: B
Explanation: Only visible for Actualtests4sure members. You can sign-up / login (it's free).
Question 5
Refer to the code below (assuming Promise.race is intended):
let cat3 = new Promise(resolve = >
setTimeout(resolve, 3000, " Cat 3 completes " )
);
Promise.race([cat1, cat2, cat3])
.then(value = > {
let result = `${value} the race.`;
})
.catch(err = > {
console.log( " Race is cancelled: " , err);
});
(Assuming cat1 and cat2 are similar to earlier examples: cat2 resolves fastest.) What is the value of result when Promise.race executes?
let cat3 = new Promise(resolve = >
setTimeout(resolve, 3000, " Cat 3 completes " )
);
Promise.race([cat1, cat2, cat3])
.then(value = > {
let result = `${value} the race.`;
})
.catch(err = > {
console.log( " Race is cancelled: " , err);
});
(Assuming cat1 and cat2 are similar to earlier examples: cat2 resolves fastest.) What is the value of result when Promise.race executes?
Correct Answer: B
Explanation: Only visible for Actualtests4sure members. You can sign-up / login (it's free).
Question 6
Given the following code:
01 counter = 0;
02 const logCounter = () = > {
03 console.log(counter);
04 };
05 logCounter();
06 setTimeout(logCounter, 2100);
07 setInterval(() = > {
08 counter++;
09 logCounter();
10 }, 1000);
What will be the first four numbers logged?
01 counter = 0;
02 const logCounter = () = > {
03 console.log(counter);
04 };
05 logCounter();
06 setTimeout(logCounter, 2100);
07 setInterval(() = > {
08 counter++;
09 logCounter();
10 }, 1000);
What will be the first four numbers logged?
Correct Answer: B
Explanation: Only visible for Actualtests4sure members. You can sign-up / login (it's free).
Question 7
Given the code below:
01 function Person(name, email) {
02 this.name = name;
03 this.email = email;
04 }
05
06 const john = new Person( ' John ' , ' [email protected] ' );
07 const jane = new Person( ' Jane ' , ' [email protected] ' );
08 const emily = new Person( ' Emily ' , ' [email protected] ' );
09
10 let usersList = [john, jane, emily];
Which method can be used to provide a visual representation of the list of users and to allow sorting by the name or email attribute?
01 function Person(name, email) {
02 this.name = name;
03 this.email = email;
04 }
05
06 const john = new Person( ' John ' , ' [email protected] ' );
07 const jane = new Person( ' Jane ' , ' [email protected] ' );
08 const emily = new Person( ' Emily ' , ' [email protected] ' );
09
10 let usersList = [john, jane, emily];
Which method can be used to provide a visual representation of the list of users and to allow sorting by the name or email attribute?
Correct Answer: A
Explanation: Only visible for Actualtests4sure members. You can sign-up / login (it's free).
