JavaScript basics · Lesson 11 of 12 · 7 minutes

JavaScript basics: Return values

return supplies a result to the caller. A function without an executed return yields undefined.

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Your objectives

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1
Build return values
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
return supplies a result to the caller. A function without an executed return yields undefined.
The requested statements are present as code, not inside a string or comment. No arbitrary JavaScript is executed.
```
function total(a, b) { return a + b; }
```
Common mistake to avoid: A string containing code executes automatically when it is assigned.
2
Extend the return values 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
return supplies a result to the caller. A function without an executed return yields undefined.
The requested statements are present as code, not inside a string or comment. No arbitrary JavaScript is executed.
```
function total(a, b) { return a + b; }
const points = total(100, 25);
```
Common mistake to avoid: A successful element lookup guarantees that the rest of an event handler is correct.
3
Verify the complete return values 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
return supplies a result to the caller. A function without an executed return yields undefined.
The requested statements are present as code, not inside a string or comment. No arbitrary JavaScript is executed.
```
function total(a, b) { return a + b; }
const points = total(100, 25);
const doubled = total(points, points);
```
Common mistake to avoid: A string containing code executes automatically when it is assigned.

Understand the pattern

return supplies a result to the caller. A function without an executed return yields undefined.

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

function total(a, b) { return a + b; }
const points = total(100, 25);
const doubled = total(points, points);

return supplies a result to the caller. A function without an executed return yields undefined.

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 return values?return supplies a result to the caller. A function without an executed return yields undefined.A string containing code executes automatically when it is assigned.A successful element lookup guarantees that the rest of an event handler is correct.

Apply it elsewhere

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

Keep the momentum.

Complete the lab, then explain and apply the pattern.

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