String Methods

Returns a new string with all letters converted to uppercase.

Part of: JavaScript Coding without HTML and CSS — Module 30

Understanding String Methods in JavaScript

What it does: toLowerCase() returns a new string with all lowercase letters. trim() cleans up whitespace at the start and end of a string. toUpperCase() converts every letter to uppercase in a new string. JavaScript uses camelCase, so it must be toUpperCase. Without (), the method isn't actually called. JavaScript is case-sensitive, so it must be lowercase 'trim'. JavaScript's built-in method is toUpperCase(), not touppercase().

Common mistakes: 'trim' must be lowercase - a capital T causes an error. Method names are camelCase - it should be toUpperCase, not touppercase.

Class: _____________________ · Name: _____________________ · Date: _________

Free printable worksheet with full answer key — or add this module to a class and your students practise it interactively.

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This module's key terms are also in a printable crossword (Modules 21–30) and word search (Modules 21–52).

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Each concept is reinforced from every angle — learned, then applied, then tested.

Learning

Duo

Does toUpperCase() return a new string in all caps?

YesNo

Matches

text.touppercase()

↓

Wrong - method names are camelCase: toUpperCase

Applying

Meanings

Term

toUpperCase()

Meaning

Returns a new string with all letters converted to uppercase.

Practice

let name = " Sam ";

Testing

Gaps

console.log(name.());

Check Answer

Spots

1let a = " hi ";

2console.log(a.Trim());

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Quick Questions

1. Does toUpperCase() return a new string in all caps?

A. Yes ✓

B. No

toUpperCase() converts every letter to uppercase in a new string.

2. Does toLowerCase() change the original string?

A. No ✓

B. Yes

toLowerCase() returns a new string - the original stays the same.

3. Does trim() remove whitespace from the start and end?

A. Yes ✓

B. No

trim() strips leading and trailing whitespace from a string.

4. Is 'touppercase' with no capitals valid JavaScript syntax?

A. Yes

B. No ✓

JavaScript uses camelCase, so it must be toUpperCase.

5. Do these string methods need parentheses to be called?

A. No

B. Yes ✓

Without (), the method isn't actually called.

Match the Pairs

name.toUpperCase() → Returns name in all uppercase letters

name.trim() → Returns name with whitespace removed from both ends

Converts every letter of a string to lowercase → text.toLowerCase()

Removes leading and trailing whitespace from a string → input.trim()

text.touppercase() → Wrong - method names are camelCase: toUpperCase

text.Trim() → Wrong - 'trim' must start with a lowercase t

Key Term

toUpperCase()

Returns a new string with all letters converted to uppercase.

Fill in the Blanks

1. console.log(name.toUpperCase());

Hint: Type the method that converts a string to all uppercase.

2. console.log(name.toLowerCase());

Hint: Type the method that converts a string to all lowercase.

3. console.log(name.trim());

Hint: Type the method that removes whitespace from both ends.

4. let upper = word.toUpperCase();

Hint: Type the method that converts a string to all uppercase.

5. let trimmed = input.trim();

Hint: Type the method that removes whitespace from both ends.

Spot the Error

Question 1

A let a = " hi ";

B console.log(a.Trim());

C console.log(a);

Line B — 'trim' must be lowercase - a capital T causes an error.

Question 2

A let b = "Hi";

B console.log(b.touppercase());

C console.log(b);

Line B — Method names are camelCase - it should be toUpperCase, not touppercase.

Question 3

A let f = "Hi";

B console.log(f);

C console.log(f.toUpperCase);

Line C — Missing parentheses - toUpperCase() needs to be called.

Question 4

A console.log(g.trim);

B let g = " hi ";

C console.log(g);

Line A — Missing parentheses - trim() needs to be called.

Question 5

A let h = "Hi";

B console.log(h.toUpperCase());

C console.log(h);

D console.log(h.touppercase());

Line D — Method names are camelCase - it should be toUpperCase, not touppercase.

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