Assignment operators in Javascript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the = operator do in JavaScript?

The = operator assigns the value on the right to the variable on the left. For example, x = 5 sets the variable x to 5.

beginner

What is the difference between = and += operators?

= assigns a value directly, while += adds the right value to the left variable and then assigns the result back. For example, x += 3 means x = x + 3.

beginner

List three compound assignment operators in JavaScript besides +=.

Three common compound assignment operators are:<br>1. -= (subtract and assign)<br>2. *= (multiply and assign)<br>3. /= (divide and assign)

intermediate

What happens if you use x ||= y in JavaScript?

The ||= operator assigns y to x only if x is falsy (like null, undefined, 0, or ''). It's a shortcut for x || (x = y).

intermediate

Explain the difference between &= and ^= operators.

&= performs a bitwise AND between the variable and the right value, then assigns the result back.<br>^= performs a bitwise XOR (exclusive OR) between the variable and the right value, then assigns the result back.

What does the operator += do in JavaScript?

A Adds the right value to the left variable and assigns the result to the left variable

B Assigns the right value to the left variable without change

C Subtracts the right value from the left variable

D Multiplies the left variable by the right value

+= adds the right value to the left variable and stores the result back in the left variable.

Which operator assigns a value only if the left variable is falsy?

A +=

B ||=

C &&=

D *=

||= assigns the right value only if the left variable is falsy.

What does x &= y do?

A Performs bitwise OR between x and y, then assigns to x

B Adds x and y, then assigns to x

C Assigns y to x if x is falsy

D Performs bitwise AND between x and y, then assigns to x

&= performs bitwise AND and assigns the result to the left variable.

Which operator multiplies and assigns in one step?

A *=

B /=

C +=

D -=

*= multiplies the left variable by the right value and assigns the result back.

What is the result of let x = 5; x ||= 10;?

A x is 10

B x is 15

C x is 5

D Error

Since 5 is truthy, ||= does not assign 10 to x, so x remains 5.

Explain how compound assignment operators work in JavaScript with examples.

Think about how you can shorten 'x = x + 3' using a compound operator.

Describe the purpose and behavior of logical assignment operators like ||= and &&=.

Consider how these operators help assign values only under certain conditions.