Syntax errors: missing quotes, brackets and braces

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which line causes a SyntaxError?

A console.log("Hello);

B console.log("Hello");

2. True or false: a program with a SyntaxError will run until it reaches the broken line, then stop.

A True: the lines before the error still run

B False: JavaScript reads the code first, so nothing runs until the syntax is fixed

3. Which if statement has a missing closing brace?

A if (age > 12) { console.log("Teen");

B if (age > 12) { console.log("Teen"); }

4. What does a SyntaxError message tell you?

A Your code ran but gave the wrong answer

B Your code broke JavaScript's rules and can't be read

5. Which line has a missing closing bracket?

A console.log("Score: " + score;

B console.log("Score: " + score);

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1console.log("Hello);		Aif (age >= 13) { console.log("Teen"); }
2SyntaxError: Unexpected token '}'		BA string that is never closed, because the closing quote is missing. This causes a SyntaxError.
3Every opening curly brace { needs a matching closing brace } to avoid a SyntaxError		CThe closing brace } is missing at the end of the loop, so JavaScript gives a SyntaxError. Add } on a new line after console.log(i);
4Every opening quote needs a matching closing quote so the string is complete		DThe closing bracket ) is missing after the condition, so JavaScript gives a SyntaxError. It should be if (score > 50) {
5if (score > 50 { console.log("Pass"); }		EJavaScript found a symbol it did not expect, often because brackets or braces do not pair up.
6for (let i = 0; i < 3; i++) { console.log(i);		Flet name = "Ava";

Definitions

SyntaxError

Fill in the Blanks

Complete each line of code by filling in the missing parts.

// Both quotes are here, so this runs ___ pet = "Rex";

function greet() { console.log("Hi"); _

// A missing quote causes a ___________ console.log("Hi");

// Unexpected _____ = stray symbol console.log("Hi");

__ (score > 50) { console.log("Pass"); }

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A let name = "Ava";

B console.log("Hi + name);

C console.log(name);

Question 2

A let score = 10;

B if (score > 5) {

C console.log("Pass");

D )

E console.log("Done");

Question 3

A let a = 2;

B let b = 3;

C console.log(a + b;

Question 4

A let name = "Mia";

B let age = 13;

C let city = Perth";

D console.log(city);

Question 5

A let temp = 30;

B let hot = temp > 25;

C if (hot {

D console.log("Hot");

E }

Answer Key

Syntax errors: missing quotes, brackets and braces

Section A: Quick Questions

A — console.log("Hello);

B — False: JavaScript reads the code first, so nothing runs until the syntax is fixed

A — if (age > 12) { console.log("Teen");

B — Your code broke JavaScript's rules and can't be read

A — console.log("Score: " + score;

Section B: Match the Pairs

console.log("Hello); → A string that is never closed, because the closing quote is missing. This causes a SyntaxError.

SyntaxError: Unexpected token '}' → JavaScript found a symbol it did not expect, often because brackets or braces do not pair up.

Every opening curly brace { needs a matching closing brace } to avoid a SyntaxError → if (age >= 13) { console.log("Teen"); }

Every opening quote needs a matching closing quote so the string is complete → let name = "Ava";

if (score > 50 { console.log("Pass"); } → The closing bracket ) is missing after the condition, so JavaScript gives a SyntaxError. It should be if (score > 50) {

for (let i = 0; i < 3; i++) { console.log(i); → The closing brace } is missing at the end of the loop, so JavaScript gives a SyntaxError. Add } on a new line after console.log(i);

Section C: Definitions

SyntaxError — An error shown when code breaks JavaScript's rules, like a missing quote, bracket or brace. JavaScript can't read the code, so the program won't run until you fix it.

Section D: Fill in the Blanks

// Both quotes are here, so this runs
let pet = "Rex";

function greet() {
  console.log("Hi");
}

// A missing quote causes a SyntaxError
console.log("Hi");

// Unexpected token = stray symbol
console.log("Hi");

if (score > 50) {
  console.log("Pass");
}

Section E: Spot the Error

B — The string "Hi " is missing its closing quote, so JavaScript throws a SyntaxError (unclosed string). It should be console.log("Hi " + name);

D — The block that opened with { must be closed with a closing brace }, not a bracket ). This causes a SyntaxError. Line 4 should be }.

C — The closing bracket ) is missing, so console.log( is never closed. JavaScript gives a SyntaxError. It should be console.log(a + b);

C — The opening quote before Perth is missing, so the string is not written correctly and gives a SyntaxError. It should be let city = "Perth";

C — The condition is missing its closing bracket ) before the {. This is a SyntaxError. It should be if (hot) {