Assignment = versus equality ===

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which line stores the value 10 in the variable score?

A score = 10;

B score === 10;

2. Which expression checks whether score is equal to 10?

A score === 10

B score = 10

3. How should you read this line aloud: lives = 3;

A lives is equal to 3

B lives becomes 3

4. How should you read this condition aloud: age === 13

A age is equal to 13

B age becomes 13

5. Which if statement is written correctly to check if x is 5?

A if (x = 5) {

B if (x === 5) {

Match the Pairs

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

Left column		Right column
1let score = 10;		AA single = assigns 5 to x instead of comparing. The condition should use === to ask 'is x equal to 5?'
2score === 10		BStores the value 10 in the variable score (score becomes 10)
3Read = as 'becomes' when you store a value in a variable		CChecks if score is equal to 10 and gives true or false
4Use === inside an if to ask 'is it equal to?'		Dif (lives === 0) {
5if (x = 5) {		Elet lives = 3;
6let age === 13;		F=== compares values, so it cannot store 13 in age. A single = is needed to assign the value.

Definitions

= vs ===

Fill in the Blanks

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

let score _ 10;

let score = 10; if (score ___ 10) console.log("Win");

let lives = 0; console.log(lives ___ 0);

let isReady = false; isReady _ true; console.log(isReady);

let n = 7; if (n ___ 7) { console.log("Lucky"); }

Spot the Error

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

Question 1

A let score = 10;

B let target = 10;

C console.log("Checking");

D if (score = target) {

E console.log("Match!");

F }

Question 2

A let lives = 3;

B console.log("Start");

C if (lives = 0) {

D console.log("Game over");

E }

Question 3

A let x = 2;

B let y = 3;

C console.log(x);

D x === y + 1;

E console.log(x);

Question 4

A let password = "abc";

B let guess = "abc";

C if (guess = password) {

D console.log("Welcome");

E }

Question 5

A let lives;

B lives === 3;

C console.log(lives);

Answer Key

Assignment = versus equality ===

Section A: Quick Questions

A — score = 10;

A — score === 10

B — lives becomes 3

A — age is equal to 13

B — if (x === 5) {

Section B: Match the Pairs

let score = 10; → Stores the value 10 in the variable score (score becomes 10)

score === 10 → Checks if score is equal to 10 and gives true or false

Read = as 'becomes' when you store a value in a variable → let lives = 3;

Use === inside an if to ask 'is it equal to?' → if (lives === 0) {

if (x = 5) { → A single = assigns 5 to x instead of comparing. The condition should use === to ask 'is x equal to 5?'

let age === 13; → === compares values, so it cannot store 13 in age. A single = is needed to assign the value.

Section C: Definitions

= vs === — A single = stores a value in a variable (x becomes 5). Triple === compares two values and gives true or false (x is equal to 5). Writing if (x = 5) is a bug.

Section D: Fill in the Blanks

let score = 10;

let score = 10;
if (score === 10) console.log("Win");

let lives = 0;
console.log(lives === 0);

let isReady = false;
isReady = true;
console.log(isReady);

let n = 7;
if (n === 7) { console.log("Lucky"); }

Section E: Spot the Error

D — A single = stores a value, so this sets score to target instead of comparing them. To ask 'is equal to' you need ===: if (score === target) {

C — if (lives = 0) stores 0 in lives instead of checking it. The condition should compare with ===: if (lives === 0) {

D — This line should store a new value in x, so it needs a single = (x becomes y + 1). === only compares and would leave x unchanged. Correct line: x = y + 1;

C — A single = overwrites guess with password, so the check is not a real comparison. Use === to ask if they are equal: if (guess === password) {

B — To give lives a value you read = as 'becomes': lives = 3;. === only compares two values and does not store anything.