JavaScript basics · Lesson 6 of 12 · 7 minutes

JavaScript basics: Conditional branches

An if statement chooses a path from a condition; the else branch handles the other case.

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Your objectives

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1
Build conditional branches
Build this first target: the JavaScript statements shown in the example, as executable-position code rather than a string or comment. Explain how the values and control flow implement this lesson’s concept; this browser lab checks structure without executing arbitrary JavaScript.
Hint & worked example
An if statement chooses a path from a condition; the else branch handles the other case.
The requested statements are present as code, not inside a string or comment. No arbitrary JavaScript is executed.
```
const ready = true;
```
Common mistake to avoid: A string containing code executes automatically when it is assigned.
2
Extend the conditional branches example
Extend your file to include: the JavaScript statements shown in the example, as executable-position code rather than a string or comment. Explain how the values and control flow implement this lesson’s concept; this browser lab checks structure without executing arbitrary JavaScript.
Hint & worked example
An if statement chooses a path from a condition; the else branch handles the other case.
The requested statements are present as code, not inside a string or comment. No arbitrary JavaScript is executed.
```
const ready = true;
let message = "Waiting";
```
Common mistake to avoid: A successful element lookup guarantees that the rest of an event handler is correct.
3
Verify the complete conditional branches pattern
Finish the pattern with: the JavaScript statements shown in the example, as executable-position code rather than a string or comment. Explain how the values and control flow implement this lesson’s concept; this browser lab checks structure without executing arbitrary JavaScript.
Hint & worked example
An if statement chooses a path from a condition; the else branch handles the other case.
The requested statements are present as code, not inside a string or comment. No arbitrary JavaScript is executed.
```
const ready = true;
let message = "Waiting";
if (ready) { message = "Ready to practice"; } else { message = "Try again later"; }
```
Common mistake to avoid: A string containing code executes automatically when it is assigned.

Understand the pattern

An if statement chooses a path from a condition; the else branch handles the other case.

Misconceptions to reject

A string containing code executes automatically when it is assigned.
A successful element lookup guarantees that the rest of an event handler is correct.

This is a code-inspection lab, not a full JavaScript runtime.

Worked example and expected result

const ready = true;
let message = "Waiting";
if (ready) { message = "Ready to practice"; } else { message = "Try again later"; }

An if statement chooses a path from a condition; the else branch handles the other case.

Try a variation

Adapt the final example to a different project name while retaining its structure and relationships. A different context still needs a real browser and accessibility check.

Explain it

Which statement correctly explains conditional branches?A string containing code executes automatically when it is assigned.A successful element lookup guarantees that the rest of an event handler is correct.An if statement chooses a path from a condition; the else branch handles the other case.

Apply it elsewhere

You reuse conditional branches in a different project. What must still be verified?Only whether the source code has the same number of lines.The input values, element availability, and actual behavior in a real browser.Nothing; passing a single exercise guarantees every future use.

Keep the momentum.

Complete the lab, then explain and apply the pattern.

Next: JavaScript basics: Arrays Try an incident drill

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