How Strings Work Differently Across Languages in DSA Typescript - Code Step by Step

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get the length of the string.

DSA Typescript

const str = "hello";
const length = str[1];

Drag options to blanks, or click blank then click option'

A.count

B.size

C.length

D.length()

Attempts:

3 left

💡 Hint

Common Mistakes

Using .length() with parentheses causes an error.

Using .size or .count which are not valid for strings in TypeScript.

In TypeScript, strings have a length property (without parentheses) to get their length.

2fill in blank

medium

Complete the code to get the character at index 2.

DSA Typescript

const str = "world";
const char = str[1];

Drag options to blanks, or click blank then click option'

A.charCodeAt(2)

B.charAt(2)

C.getChar(2)

D[2]

Attempts:

3 left

💡 Hint

Common Mistakes

Using .getChar(2) which does not exist.

Using .charCodeAt(2) returns the Unicode number, not the character.

In TypeScript, you can access characters in a string using bracket notation like str[2].

3fill in blank

hard

Fix the error in the code to convert string to uppercase.

DSA Typescript

const str = "hello";
const upper = str[1];

Drag options to blanks, or click blank then click option'

A.toUpperCase()

B.toUpperCase

C.uppercase()

D.toUpper()

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting parentheses causes the variable to hold the function, not the result.

Using incorrect method names like .uppercase() or .toUpper().

The correct method to convert a string to uppercase in TypeScript is toUpperCase() with parentheses.

4fill in blank

hard

Fill both blanks to create a new string by repeating 'abc' 3 times.

DSA Typescript

const base = "abc";
const repeated = base[1]([2]);

Drag options to blanks, or click blank then click option'

A.repeat

B3

C2

D.times

Attempts:

3 left

💡 Hint

Common Mistakes

Using .times which does not exist.

Passing wrong number of repetitions.

Use the repeat method with the number of times to repeat as argument.

5fill in blank

hard

Fill all three blanks to create a new string by slicing 'typescript' from index 4 to 7.

DSA Typescript

const lang = "typescript";
const part = lang[1]([2], [3]);

Drag options to blanks, or click blank then click option'

A.slice

B4

C7

D.substring

Attempts:

3 left

💡 Hint

Common Mistakes

Using .substring which works differently with indexes.

Mixing up start and end indexes.

The slice method extracts part of a string from start index to end index (not including end).

Practice

1. In TypeScript, what is the type of a string when you use single quotes like 'hello' compared to double quotes like "hello"?

easy

A. Both are of type string and behave the same

B. Single quotes create a character, double quotes create a string

C. Single quotes create a string, double quotes create a character

D. Single quotes are invalid syntax in TypeScript

Solution

1. Step 1: Understand string literals in TypeScript

   TypeScript treats both single and double quotes as string delimiters, so both create string values.

2. Step 2: Confirm no character type in TypeScript

   Unlike some languages, TypeScript does not have a separate character type; single quotes do not create characters.

3. Final Answer:

   Both are of type string and behave the same -> Option A

4. Quick Check:

   Single and double quotes create strings = A [OK]

Hint: Single and double quotes both create strings in TypeScript [OK]

Common Mistakes:

• Thinking single quotes create characters
• Confusing TypeScript with languages like C
• Assuming single quotes are invalid

2. Which of the following is the correct way to declare a multi-line string in TypeScript?

easy

A. Using double quotes with + operator: const s = "line1" + "line2";

B. Using single quotes with \n: const s = 'line1\nline2';

C. Using backticks: const s = `line1\nline2`;

D. Using triple quotes: const s = '''line1\nline2''';

Solution

1. Step 1: Identify multi-line string syntax in TypeScript

   TypeScript supports template literals using backticks (`) which allow multi-line strings directly.

2. Step 2: Check other options for correctness

   Single and double quotes require explicit \n for new lines; triple quotes are invalid in TypeScript.

3. Final Answer:

   Using backticks: const s = `line1\nline2`; -> Option C

4. Quick Check:

   Backticks allow multi-line strings = A [OK]

Hint: Use backticks for multi-line strings in TypeScript [OK]

Common Mistakes:

• Using triple quotes like Python
• Expecting single or double quotes to support multi-line directly
• Forgetting to escape newlines in single/double quotes

3. What will be the output of the following TypeScript code?

const s = `Hello\nWorld`;
console.log(s.length);

medium

A. Error

B. 12

C. 10

D. 11

Solution

1. Step 1: Understand the string content

   The string is a template literal with an actual newline character between Hello and World, not the two-character escape sequence.

2. Step 2: Count characters including the newline

   Characters: H(1) e(2) l(3) l(4) o(5) \n is a single newline character (counts as 1), W(6) o(7) r(8) l(9) d(10). So length is 11.

3. Final Answer:

   11 -> Option D

4. Quick Check:

   Template literals interpret \n as newline character = A [OK]

Hint: Template literals interpret \n as a single newline character [OK]

Common Mistakes:

• Assuming \n is two characters in length
• Counting only visible characters
• Expecting runtime error due to escape

4. Identify the error in this TypeScript code snippet:

const greeting = 'Hello;
console.log(greeting);

medium

A. Missing closing single quote for the string

B. Incorrect use of backticks instead of single quotes

C. Missing semicolon after console.log statement

D. No error, code runs fine

Solution

1. Step 1: Check string syntax

   The string starts with a single quote but does not have a closing single quote before the newline.

2. Step 2: Understand string literal rules

   Single-quoted strings cannot span multiple lines without escape; missing closing quote causes syntax error.

3. Final Answer:

   Missing closing single quote for the string -> Option A

4. Quick Check:

   Unclosed string literal = D [OK]

Hint: Strings must be closed before newline unless using backticks [OK]

Common Mistakes:

• Thinking backticks are required here
• Ignoring missing quote errors
• Assuming semicolon omission causes error

5. Given the following TypeScript code, what will be the output?

const s1 = 'café';
const s2 = 'cafe\u0301';
console.log(s1 === s2);

Note: \u0301 is a Unicode combining acute accent.

hard

A. true

B. false

C. SyntaxError

D. RuntimeError

Solution

1. Step 1: Understand Unicode normalization in strings

   s1 uses a single character 'é' (U+00E9), while s2 uses 'e' plus combining accent (U+0301).

2. Step 2: Compare strings with different Unicode forms

   Direct equality compares code units; different Unicode sequences mean s1 !== s2.

3. Final Answer:

   false -> Option B

4. Quick Check:

   Unicode composed vs decomposed forms differ = C [OK]

Hint: Unicode composed and decomposed strings are not equal by default [OK]

Common Mistakes:

• Assuming visually same means equal
• Ignoring Unicode combining characters
• Expecting automatic normalization in equality