CodeHS – JavaScript Questions and
Answers Already Passed
What is JavaScript used for?
✔✔JavaScript is used to create interactive and dynamic web pages.
How do you declare a variable in JavaScript?
✔✔You declare a variable in JavaScript using `var`, `let`, or `const`.
What is the purpose of the `alert()` function in JavaScript?
✔✔The `alert()` function displays a popup message to the user.
How do you write a comment in JavaScript?
✔✔You write a comment in JavaScript using `//` for single-line comments or `/* */` for multi-
line comments.
What does the `console.log()` function do?
✔✔The `console.log()` function outputs messages to the browser's console for debugging.
1
,How do you create a function in JavaScript?
✔✔You create a function using the `function` keyword followed by the function name and
parentheses.
What is the purpose of a `for` loop in JavaScript?
✔✔A `for` loop is used to repeat a block of code a specific number of times.
How do you check if a condition is true in JavaScript?
✔✔You check a condition using an `if` statement.
What is the purpose of the `return` statement in a function?
✔✔The `return` statement sends a value back from a function to the caller.
How do you concatenate strings in JavaScript?
✔✔You concatenate strings using the `+` operator.
What is an array in JavaScript?
✔✔An array is a collection of values stored in a single variable.
2
,How do you access the first element of an array?
✔✔You access the first element of an array using `array[0]`.
What does the `length` property of an array do?
✔✔The `length` property returns the number of elements in an array.
How do you add an element to the end of an array?
✔✔You add an element to the end of an array using the `push()` method.
What is the purpose of the `Math.random()` function?
✔✔The `Math.random()` function generates a random number between 0 and 1.
How do you round a number in JavaScript?
✔✔You round a number using the `Math.round()` function.
What does the `typeof` operator do?
✔✔The `typeof` operator returns the type of a variable or value.
3
, How do you convert a string to a number in JavaScript?
✔✔You convert a string to a number using `parseInt()` or `parseFloat()`.
What is an object in JavaScript?
✔✔An object is a collection of key-value pairs that can store data and methods.
How do you access a property of an object?
✔✔You access a property of an object using dot notation or bracket notation.
What is the difference between `let` and `const`?
✔✔`let` allows reassignment of the variable, while `const` makes the variable constant.
What is a callback function?
✔✔A callback function is a function passed as an argument to another function and executed
later.
How do you handle errors in JavaScript?
4
Answers Already Passed
What is JavaScript used for?
✔✔JavaScript is used to create interactive and dynamic web pages.
How do you declare a variable in JavaScript?
✔✔You declare a variable in JavaScript using `var`, `let`, or `const`.
What is the purpose of the `alert()` function in JavaScript?
✔✔The `alert()` function displays a popup message to the user.
How do you write a comment in JavaScript?
✔✔You write a comment in JavaScript using `//` for single-line comments or `/* */` for multi-
line comments.
What does the `console.log()` function do?
✔✔The `console.log()` function outputs messages to the browser's console for debugging.
1
,How do you create a function in JavaScript?
✔✔You create a function using the `function` keyword followed by the function name and
parentheses.
What is the purpose of a `for` loop in JavaScript?
✔✔A `for` loop is used to repeat a block of code a specific number of times.
How do you check if a condition is true in JavaScript?
✔✔You check a condition using an `if` statement.
What is the purpose of the `return` statement in a function?
✔✔The `return` statement sends a value back from a function to the caller.
How do you concatenate strings in JavaScript?
✔✔You concatenate strings using the `+` operator.
What is an array in JavaScript?
✔✔An array is a collection of values stored in a single variable.
2
,How do you access the first element of an array?
✔✔You access the first element of an array using `array[0]`.
What does the `length` property of an array do?
✔✔The `length` property returns the number of elements in an array.
How do you add an element to the end of an array?
✔✔You add an element to the end of an array using the `push()` method.
What is the purpose of the `Math.random()` function?
✔✔The `Math.random()` function generates a random number between 0 and 1.
How do you round a number in JavaScript?
✔✔You round a number using the `Math.round()` function.
What does the `typeof` operator do?
✔✔The `typeof` operator returns the type of a variable or value.
3
, How do you convert a string to a number in JavaScript?
✔✔You convert a string to a number using `parseInt()` or `parseFloat()`.
What is an object in JavaScript?
✔✔An object is a collection of key-value pairs that can store data and methods.
How do you access a property of an object?
✔✔You access a property of an object using dot notation or bracket notation.
What is the difference between `let` and `const`?
✔✔`let` allows reassignment of the variable, while `const` makes the variable constant.
What is a callback function?
✔✔A callback function is a function passed as an argument to another function and executed
later.
How do you handle errors in JavaScript?
4
