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JS Playground 2
Introduction
Welcome to JavaScript Playground Level 2! This set of exercises focuses on understanding JavaScript data types, arrays, objects, and basic programming logic. You'll explore how different operations affect data types and learn to work with arrays and objects effectively.
Pay close attention to the subtle differences between data types and how JavaScript handles type coercion in various scenarios.
Questions
1. Data type identification
What is the data type of 2021?
2. Addition result type
What is the data type of the result of 1 + 12?
3. Type coercion
What is the data type of the result of 20 + '21'?
4. Array indexing
Given the array: let myArray = [1, 2, 3, 4];
What is the value of myArray[3]?
5. Last array element
Given the array: let myArray = [1, 2, 3, 4];
What is the value of myArray[myArray.length-1]?
6. Out of bounds access
Given the array: let myArray = [1, 2, 3, 4];
What is the value of myArray[myArray.length]?
7. Object property access
Given the object: let formData = { name: 'Jon', thingsKnown: ['Swordsmanship', 'Honor'] };
How do you print out what Jon knows? (Multiple answers possible)
8. Object property assignment
Given the object: let formData = { name: 'Jon', workPlace: 'Night Watch' };
To set the workPlace to 'The Wall' you can run: (Multiple answers possible)
9. String concatenation
What is the result of the following code?
let message = 'Coding is ' + 'VERY' + ' easy!';
10. Boolean evaluation
What will be logged to the console after running this code snippet?
console.log(5 > 10);
11. Conditional logic
Will you have dinner?
let age = 25;
if (age >= 18) {
console.log('Yes');
} else {
console.log('No');
}
12. Array truthiness check
Given the following code:
if (arr.length > 0) {
console.log('arr is not empty');
} else {
console.log('arr is empty');
}
Choose the value of arr to get the result 'arr is not empty'. (Multiple answers possible)
13. Truthy array evaluation
Given the following code:
if (arr) {
console.log('arr is truthy');
} else {
console.log('arr is falsy');
}
Choose the value of arr to get the result 'arr is truthy'. (Multiple answers possible)
14. String template evaluation
What is the value of result after executing the following code?
let name = 'Bran Stark';
let age = 10;
let result = name + ' is ' + (age >= 18 ? 'an adult' : 'not an adult');