Dynamic typing in JavaScript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does dynamic typing mean in JavaScript?

Dynamic typing means variables can hold any type of value and their type can change during the program's execution.

beginner

How do you declare a variable in JavaScript that can hold any type of value?

You can use let or var to declare a variable without specifying its type, allowing it to hold any value.

beginner

What happens when you assign a number to a variable and then assign a string to the same variable?

The variable changes its type from number to string because JavaScript variables are dynamically typed.

beginner

Show an example of dynamic typing in JavaScript.

Example:<br><pre>let value = 10;  // value is a number
value = "hello";  // now value is a string</pre>

beginner

Why is dynamic typing useful in JavaScript?

It makes coding faster and more flexible because you don't have to declare variable types explicitly.

What type can a JavaScript variable hold?

A Only strings

B Only numbers

C Any type, and it can change during execution

D Only one type fixed at declaration

JavaScript variables are dynamically typed, so they can hold any type and change types.

Which keyword allows you to declare a variable that can change type in JavaScript?

A let

B int

C string

D const

let declares a variable that can hold any type and can be reassigned.

What happens if you assign a string to a variable that previously held a number?

A The variable keeps the number

B The variable changes to hold a string

C An error occurs

D The program crashes

In dynamic typing, the variable's type changes to the new assigned value's type.

Which of these is NOT a benefit of dynamic typing?

A No need to declare types explicitly

B More flexible variable use

C Faster coding

D Automatic type safety

Dynamic typing does not guarantee type safety; errors can happen at runtime.

Which of these is an example of dynamic typing?

A let x = 5; x = 'five';

B int x = 5; x = 'five';

C const x = 5; x = 10;

D string x = 'hello'; x = 10;

In JavaScript, let x = 5; x = 'five'; shows a variable changing type dynamically.

Explain dynamic typing in JavaScript with an example.

Think about how a variable can start as a number and then hold a string.

What are the advantages and possible downsides of dynamic typing in JavaScript?

Consider both why it helps and what problems it might cause.