throw Statement
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. Does throw create a custom error?
2. Does throw stop the current code from running further?
3. Can a thrown error be caught by a catch block?
4. Must 'throw' be written in lowercase?
5. Must 'Error' start with a capital E when using new Error()?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1throw new Error("Something broke"); | Athrow | |
| 2throw new Error("Bad age"); | BWrong - 'Error' must start with a capital E | |
| 3Creates and raises a custom error | CRaises an error describing an invalid age | |
| 4Can be caught by a matching catch block | Dtry { throw new Error("X"); } catch (e) { ... } | |
| 5Throw new Error("Bad"); | EWrong - 'throw' must be lowercase | |
| 6throw new error("Bad"); | FRaises a custom error and stops execution at that point |
C
Definitions
throw
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
_____ new Error("Something broke");
2.
throw new _____("Invalid input");
3.
_____ new Error("No data found");
4.
if (age < 0) {
_____ new Error("Bad age");
}
5.
throw new _____("Out of range");
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
Throw new Error("Bad");
B
console.log("after");
C
let x = 1;
Question 2
A
throw new error("Bad");
B
console.log("after");
C
let x = 1;
Question 3
A
let a = 1;
B
throw "Bad";
C
console.log(a);
Question 4
A
let b = 2;
B
trow new Error("Bad");
C
console.log(b);
Question 5
A
try {
B
throw new Error("Oops");
C
} catch (e) {
D
console.log(e.message)
E
}
Answer Key
throw Statement
Section A: Quick Questions
Q1
A — Yes
Q2
B — Yes
Q3
A — Yes
Q4
B — Yes
Q5
A — Yes
Section B: Match the Pairs
Q1
throw new Error("Something broke"); → Raises a custom error and stops execution at that point
Q2
throw new Error("Bad age"); → Raises an error describing an invalid age
Q3
Creates and raises a custom error → throw
Q4
Can be caught by a matching catch block → try { throw new Error("X"); } catch (e) { ... }
Q5
Throw new Error("Bad"); → Wrong - 'throw' must be lowercase
Q6
throw new error("Bad"); → Wrong - 'Error' must start with a capital E
Section C: Definitions
Q1
throw — Creates a custom error and immediately stops the current code from running further.Section D: Fill in the Blanks
Q1
throw new Error("Something broke");Q2
throw new Error("Invalid input");Q3
throw new Error("No data found");Q4
if (age < 0) {
throw new Error("Bad age");
}Q5
throw new Error("Out of range");Section E: Spot the Error
Q1
A — 'throw' must be lowercase - a capital T causes an error.
Q2
A — 'Error' must start with a capital E, not lowercase.
Q3
B — This line is actually correct - throw can raise a plain string too.
Q4
B — 'throw' is misspelled as 'trow'.
Q5
D — This line is missing a semicolon, but that's not required in JS.