Salesforce Salesforce Certifications JAVASCRIPT-DEVELOPER-I Questions & Answers

• Question 171:

  Refer to the following code:

  function test (val) {

  If (val === undefined) {

  return `Undefined values!' ;

  }

  if (val === null) {

  return `Null value! ';

  }

  return val;

  }

  Let x;

  test(x);

  What is returned by the function call on line 13?

  A. Undefined

  B. Line 13 throws an error.

  C. `Undefined values!'

  D. `Null value!'

  Correct Answer: C

• Question 172:

  Refer to the string below:

  const str = 'Salesforce';

  Which two statements result in the word 'Sales'?

  Choose 2 answers

  A. str.substr(1, 5);

  B. str.substr (0, 5);

  C. str.substring (1, 5);

  D. str.substring (0, 5);

  Correct Answer: BD

• Question 173:

  Universal Containers (UC)notices that its application that allows users to search for accounts makes a network request each time a key is pressed. This results in too many requests for the server to handle.

  Address this problem, UC decides to implement a debounce function on string change handler.

  What are three key steps to implement this debounce function?

  Choose 3 answers:

  A. If there is an existing setTimeout and the search string change, allow the existing setTimeout to finish, and do not enqueue a new setTimeout.

  B. When the search string changes, enqueue the request within a setTimeout.

  C. Ensure that the network request has the property debounce set to true.

  D. If there is an existing setTimeout and the search string changes, cancel the existing setTimeout using thepersisted timerId and replace it with a new setTimeout.

  E. Store the timeId of the setTimeout last enqueued by the search string change handle.

  Correct Answer: ABC

• Question 174:

  Universal Containers (UC) just launched a new landing page, but users complain that thewebsite is slow. A developer found some functions any that might cause this problem. To verify this, the developer decides to execute everything and log the time each of these three suspicious functions consumes.

  Which function can the developer use to obtain the time spent by every one of the three functions?

  

  A. console. timeLog ()

  B. console.timeStamp ()

  C. console.trace()

  D. console.getTime ()

  Correct Answer: A

• Question 175:

  Refer to the code below:

  

  What is the output of this function when called with an empty array?

  A. Return 0

  B. Return 5

  C. Return NaN

  D. Return Infinity

  Correct Answer: B

• Question 176:

  Refer to the code below:

  Function Person(firstName, lastName, eyecolor) {

  this.firstName =firstName;

  this.lastName = lastName;

  this.eyeColor = eyeColor;

  }

  Person.job = `Developer';

  const myFather = new Person(`John', `Doe');

  console.log(myFather.job);

  What is the output after the code executes?

  A. ReferenceError: eyeColor is not defined

  B. ReferenceError: assignment to undeclared variable "Person"

  C. Developer

  D. Undefined

  Correct Answer: D

• Question 177:

  Refer tothe code below:

  function foo () {

  const a =2;

  function bat() {

  console.log(a);

  }

  return bar;

  }

  Why does the function bar have access to variable a ?

  A. Inner function's scope

  B. Hoisting

  C. Outer function's scope

  D. Prototype chain

  Correct Answer: C

• Question 178:

  Refer to code below:

  Let first = `who';

  Let second = `what';

  Try{

  Try{

  Throw new error(`Sad trombone');

  }catch (err){

  First ='Why';

  }finally {

  Second ='when';

  } catch(err) {

  Second ='Where';

  }

  What are the values for first and second once the code executes ?

  A. First is Who and second is When

  B. First is why and second is where

  C. First is who and second is where

  D. First is why and second is when

  Correct Answer: D

• Question 179:

  At Universal Containers, every team has its own way of copyingJavaScript objects. The code snippet shows an Implementation from one team: What is the output of the code execution?

  

  A. Hello John Doe

  B. Hello Dan

  C. Hello Dan Doe

  D. SyntaxError: Unexpected token in JSON

  Correct Answer: D

• Question 180:

  In which situation should a developer include a try .. catch block around their function call ?

  A. The function has an error that should not be silenced.

  B. The function results in an out of memory issue.

  C. The function might raise a runtime error that needs to be handled.

  D. The function contains scheduled code.

  Correct Answer: C