7️⃣ Ternary Operator

The ternary operator is a short way to write a simple "if...else".

Instead of:

let age = 20;

let message;

if (age >= 18) {

message = "Adult";

} else {

message = "Minor";

}

You can write:

let age = 20;

let message = age >= 18 ? "Adult" : "Minor";

console.log(message);

Output:

Adult

The structure is:

condition ? valueIfTrue : valueIfFalse

Use it for simple decisions. For complicated logic, a normal "if...else" is usually easier to read.

8️⃣ Nullish Coalescing "??"

This operator is useful when you want a fallback only when a value is "null" or "undefined".

let username = null;

let name = username ?? "Guest";

console.log(name);

Output:

Guest

Compare this with "||":

let score = 0;

console.log(score || 100);

Output:

100

But:

console.log(score ?? 100);

Output:

0

Why?

Because "0" is falsy, but it is not "null" or "undefined".

This distinction becomes very useful when working with real-world data.

9️⃣ Optional Chaining "?."

Optional chaining allows you to safely access properties that may not exist.

Without optional chaining:

let user = {};

console.log(user.address.city);

This can cause an error because "address" doesn't exist.

With optional chaining:

let user = {};

console.log(user.address?.city);

Result:

undefined

Instead of immediately throwing an error.

You'll use this frequently when working with API responses and nested objects.

🔟 Operator Precedence

JavaScript doesn't simply evaluate everything from left to right.

For example:

let result = 10 + 5 * 2;

console.log(result);

Output:

20

Multiplication happens before addition.

You can use parentheses to make the intended order clear:

let result = (10 + 5) * 2;

console.log(result);

Output:

30

When in doubt, use parentheses rather than relying on complicated precedence rules.

1️⃣1️⃣ Expressions

An expression is something that produces a value.

Examples:

10 + 5

produces:

15

Another example:

age >= 18

produces either:

true

or:

false

And:

name ?? "Guest"

produces a value.

Expressions are the building blocks of JavaScript programs.

🧠 Real-World Example

Imagine an online shopping application.

let price = 2000;

let discount = 500;

let isMember = true;

let finalPrice = price - discount;

if (isMember && finalPrice > 1000) {

console.log("Member discount applied");

}

Here you're using:

• Variables

• Arithmetic operators

• Comparison operators

• Logical operators

• Conditions

This is how basic JavaScript concepts start working together in real applications.

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