Arrow Functions
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. Does => separate the parameters from the function body in an arrow function?
2. Is -> used instead of => in JavaScript arrow functions?
3. Do arrow functions with no parameters still need empty parentheses?
4. Does an arrow function need the 'function' keyword?
5. Can an arrow function with a single parameter omit the parentheses?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1(a, b) => a + b | ADoubles x using a single-parameter arrow function | |
| 2x => x * 2 | BAdds a and b together using an arrow function | |
| 3A shorter way of writing a function expression | CWrong - use =>, not ->, between parameters and body | |
| 4Required even when an arrow function has no parameters | DWrong - arrow functions don't use the 'function' keyword | |
| 5let f = (a, b) -> a + b; | E=> | |
| 6let g = function (x) => x; | F() |
C
Definitions
=>
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
let add = (a, b) __ {
2.
let double = x __ x * 2;
3.
let greet = _) => "Hi";
4.
let square = (n) __ n * n;
5.
let multiply = (x, y) __ x * y;
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
let f = (a, b) -> a + b;
B
console.log(f(2, 3));
C
let g = (x) => x * 2;
Question 2
A
let h = (x) => x + 1;
B
console.log(h(5));
C
let i = function (x) => x;
Question 3
A
let j = => 5;
B
console.log(j());
C
let k = () => 10;
Question 4
A
console.log(m(1, 2));
B
let m = (a b) => a + b;
C
let n = (x) => x * x;
Question 5
A
let p = (x) => x - 1;
B
console.log(p(5));
C
let q = (y) => y + 1;
D
let r = (z) -> z * 2;
Answer Key
Arrow Functions
Section A: Quick Questions
Q1
A — Yes
Q2
A — No
Q3
B — Yes
Q4
B — No
Q5
A — Yes
Section B: Match the Pairs
Q1
(a, b) => a + b → Adds a and b together using an arrow function
Q2
x => x * 2 → Doubles x using a single-parameter arrow function
Q3
A shorter way of writing a function expression → =>
Q4
Required even when an arrow function has no parameters → ()
Q5
let f = (a, b) -> a + b; → Wrong - use =>, not ->, between parameters and body
Q6
let g = function (x) => x; → Wrong - arrow functions don't use the 'function' keyword
Section C: Definitions
Q1
=> — A shorter syntax for writing a function, placed between the parameters and the function body.Section D: Fill in the Blanks
Q1
let add = (a, b) => {Q2
let double = x => x * 2;Q3
let greet = () => "Hi";Q4
let square = (n) => n * n;Q5
let multiply = (x, y) => x * y;Section E: Spot the Error
Q1
A — Arrow functions use =>, not ->, between parameters and body.
Q2
C — Arrow functions don't use the 'function' keyword - remove it.
Q3
A — Arrow functions with no parameters need empty parentheses: ().
Q4
B — Multiple parameters need a comma between them: (a, b).
Q5
D — Arrow functions use =>, not ->, between parameters and body.