Salesforce JavaScript Developer I Cert
Practice Exam 2023/2024
Which two syntax examples correctly initialize a value to the variable strLang?
A. let strLang = 'javascript';
B. const strLang = 'java' + 'script';
C. let strLang = javascript;
D. str strLang = 'javascript'; - ANSWER-ANSWER:
A. let strLang = 'javascript';
B. const strLang = 'java' + 'script';
Additional Info:
Note that C doesn't have a value that has single quotes around the word 'javascript' and for D, 'str' is not
a proper identifier
Which statement sorts the following number array so it is in ascending order? const arr = [7, 3, 400, 10];
A. arr.sort();
B. arr.sort((a, b) => a - b);
C. arr.sort((a, b) => a < b);
D. arr.sort((a, b) => b - a); - ANSWER-ANSWER:
B. arr.sort((a, b) => a - b);
Additional Info:
A. The sort() function sorts values as strings, which will sort this as [10, 3, 400, 7].
C. The compare function expects a positive, negative, or 0 to be returned.
D. The compare function will actually reverse the order of the numbers.
,Which statement sorts the following string array so it is in descending order? const arr = ["Banana",
"Orange", "Apple", "Mango"];
A. arr.sort();
B. arr.sort((a, b) => a - b);
C. arr.reverse();
D. arr.sort((a, b) => b - a); - ANSWER-ANSWER:
C. arr.reverse();
Additional Info:
A. The sort() function sorts values as strings in ASCENDING order: ["Apple", "Banana", "Mango",
"Orange"];
B,D. Expect a number array.
What are the different data types used in JavaScript? - ANSWER-ANSWER:
There are 8 basic data types in JavaScript:
1. Number for numbers of any kind: integer or floating-point, integers are limited by ±((2^53)-1).
2. BigInt is for integer numbers of arbitrary length.
3. String for strings. A string may have zero or more characters, there's no separate single-character type.
4. Boolean for true/false.
5. NULL for unknown values - a standalone type that has a single value null. Note, typeof null returns
"object" even though it is NOT and object.
6. Undefined for unassigned values - a standalone type that has a single value undefined.
7. Object for more complex data structures.
,8. Symbol for unique identifiers.
Which collections of data are ordered by a key? - ANSWER-ANSWER:
Map and set objects.
What is the proper syntax for adding placeholders in template literals? - ANSWER-ANSWER:
Use a dollar sign followed by curly brackets:
${expression}.
Additional Info:
let name = "John";
// embed a variable
alert( `Hello, ${name}!` ); // Hello, John!
// embed an expression
alert( `the result is ${1 + 2}` ); // the result is 3
Note this only works if you use backticks, `, and not single(') or double(") quotes otherwise the results
will be shown as literal, ie: Hello, ${name}!
How do you instantiate a value as a BigInt?
A. Nothing, JavaScript will automatically cast a number to a BigInt if the value is greater than ((2^53) - 1)
B. const bigInt = BigInt.parse(1234567890123456789012345678901234567890);
C. const bigInt = 1234567890123456789012345678901234567890n;
D. const bigInt = BigInt.parse('1234567890123456789012345678901234567890'); - ANSWER-ANSWER:
C. const bigInt = 1234567890123456789012345678901234567890n;
Additional Info:
, BigInt does NOT work in IE.
Given the following Animal constructor:
function Animal(size, age) {
this.size = size;
this.age = age;
this.canTalk = false;
}
Which method creates a new instance of the object?
A. Object.create('Animal');
B. new Animal('large', 10);
C. Object.prototype(Animal);
D. Object.new(Animal); - ANSWER-ANSWER:
B. new Animal('large', 10);
Additional Info:
A. The create method needs the object name without quotes.
C. This is an incorrect way to use a prototype. Prototypes are used to add methods to existing
constructors.
D. This is not the correct way to use the new keyword. It is not a method.
A developer wants to use a module called DatePrettyPrint. This module exports one default function
called printDate().
How can a developer import and use the printDate() function?
A. import printDate() from '/path/DatePrettyPrint.js';
printDate();
B. import printDate from '/path/DatePrettyPrint.js';
printDate();
Practice Exam 2023/2024
Which two syntax examples correctly initialize a value to the variable strLang?
A. let strLang = 'javascript';
B. const strLang = 'java' + 'script';
C. let strLang = javascript;
D. str strLang = 'javascript'; - ANSWER-ANSWER:
A. let strLang = 'javascript';
B. const strLang = 'java' + 'script';
Additional Info:
Note that C doesn't have a value that has single quotes around the word 'javascript' and for D, 'str' is not
a proper identifier
Which statement sorts the following number array so it is in ascending order? const arr = [7, 3, 400, 10];
A. arr.sort();
B. arr.sort((a, b) => a - b);
C. arr.sort((a, b) => a < b);
D. arr.sort((a, b) => b - a); - ANSWER-ANSWER:
B. arr.sort((a, b) => a - b);
Additional Info:
A. The sort() function sorts values as strings, which will sort this as [10, 3, 400, 7].
C. The compare function expects a positive, negative, or 0 to be returned.
D. The compare function will actually reverse the order of the numbers.
,Which statement sorts the following string array so it is in descending order? const arr = ["Banana",
"Orange", "Apple", "Mango"];
A. arr.sort();
B. arr.sort((a, b) => a - b);
C. arr.reverse();
D. arr.sort((a, b) => b - a); - ANSWER-ANSWER:
C. arr.reverse();
Additional Info:
A. The sort() function sorts values as strings in ASCENDING order: ["Apple", "Banana", "Mango",
"Orange"];
B,D. Expect a number array.
What are the different data types used in JavaScript? - ANSWER-ANSWER:
There are 8 basic data types in JavaScript:
1. Number for numbers of any kind: integer or floating-point, integers are limited by ±((2^53)-1).
2. BigInt is for integer numbers of arbitrary length.
3. String for strings. A string may have zero or more characters, there's no separate single-character type.
4. Boolean for true/false.
5. NULL for unknown values - a standalone type that has a single value null. Note, typeof null returns
"object" even though it is NOT and object.
6. Undefined for unassigned values - a standalone type that has a single value undefined.
7. Object for more complex data structures.
,8. Symbol for unique identifiers.
Which collections of data are ordered by a key? - ANSWER-ANSWER:
Map and set objects.
What is the proper syntax for adding placeholders in template literals? - ANSWER-ANSWER:
Use a dollar sign followed by curly brackets:
${expression}.
Additional Info:
let name = "John";
// embed a variable
alert( `Hello, ${name}!` ); // Hello, John!
// embed an expression
alert( `the result is ${1 + 2}` ); // the result is 3
Note this only works if you use backticks, `, and not single(') or double(") quotes otherwise the results
will be shown as literal, ie: Hello, ${name}!
How do you instantiate a value as a BigInt?
A. Nothing, JavaScript will automatically cast a number to a BigInt if the value is greater than ((2^53) - 1)
B. const bigInt = BigInt.parse(1234567890123456789012345678901234567890);
C. const bigInt = 1234567890123456789012345678901234567890n;
D. const bigInt = BigInt.parse('1234567890123456789012345678901234567890'); - ANSWER-ANSWER:
C. const bigInt = 1234567890123456789012345678901234567890n;
Additional Info:
, BigInt does NOT work in IE.
Given the following Animal constructor:
function Animal(size, age) {
this.size = size;
this.age = age;
this.canTalk = false;
}
Which method creates a new instance of the object?
A. Object.create('Animal');
B. new Animal('large', 10);
C. Object.prototype(Animal);
D. Object.new(Animal); - ANSWER-ANSWER:
B. new Animal('large', 10);
Additional Info:
A. The create method needs the object name without quotes.
C. This is an incorrect way to use a prototype. Prototypes are used to add methods to existing
constructors.
D. This is not the correct way to use the new keyword. It is not a method.
A developer wants to use a module called DatePrettyPrint. This module exports one default function
called printDate().
How can a developer import and use the printDate() function?
A. import printDate() from '/path/DatePrettyPrint.js';
printDate();
B. import printDate from '/path/DatePrettyPrint.js';
printDate();
