Function parameters in Javascript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are function parameters in JavaScript?

Function parameters are names listed in a function definition. They act like placeholders for values that the function will receive when called.

beginner

How do you define a function with two parameters named a and b?

You write: <br><pre>function example(a, b) {<br>  // code here<br>}</pre>

intermediate

What happens if you call a function with fewer arguments than parameters?

The missing parameters get the value undefined. You can check for this inside the function to handle missing values.

intermediate

What is a default parameter value in JavaScript functions?

A default parameter value is a value assigned to a parameter in the function definition. It is used if no argument is passed for that parameter when the function is called.

beginner

How do you write a function with a default parameter value of 10 for parameter num?

You write: <br><pre>function example(num = 10) {<br>  // code here<br>}</pre>

What will be the value of b when calling function test(a, b) {} as test(5)?

A null

B 5

C undefined

D 0

If you call a function with fewer arguments than parameters, the missing parameters get the value undefined.

How do you assign a default value of 100 to a parameter x in a function?

A function f(x <- 100) {}

B function f(x: 100) {}

C function f(x == 100) {}

D function f(x = 100) {}

The correct syntax for default parameters in JavaScript is function f(x = 100) {}.

Which of the following is true about function parameters?

A Parameters are placeholders for values passed to functions.

B Parameters store the return value of a function.

C Parameters are only used outside the function.

D Parameters must always have default values.

Parameters are names used inside function definitions to receive values when the function is called.

What happens if you call a function with more arguments than parameters?

A It causes a syntax error.

B Extra arguments are ignored unless accessed via special objects.

C The function automatically creates new parameters.

D The function stops running.

Extra arguments are ignored by named parameters but can be accessed using the arguments object or rest parameters.

Which keyword is used to collect multiple function arguments into an array?

A rest parameter (...)

B spread operator (...)

C default parameter

D arguments

The rest parameter syntax ...name collects multiple arguments into an array.

Explain what function parameters are and how they work in JavaScript.

Think about how functions get information to work with.

Describe how to use default parameter values and why they are useful.

Consider what happens when a function is called without some arguments.