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Computer Science AS OCR

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Exam code:H046

Strings in JavaScript

  • A string is a sequence of characters enclosed in single quotes (') or double quotes (")

  • Strings are widely used for representing and manipulating text-based data

Creating strings

  • Strings can be created in JavaScript by enclosing text within quotes:

const message = 'Hello, world!';
const name = "John Doe";

String length

  • To find the length of a string, use the length property

  • The length property returns the number of characters in a string:

const message = 'Hello, world!';
console.log(message.length);

// Output: 13

  • In this example, the length property is used to determine the number of characters in the message string

Substring extraction

  • To extract a portion of a string, use the substring() method

  • The substring() method takes two parameters: the starting index and the ending index (optional)

  • A new string is returned containing the characters within the specified range:

const message = 'Hello, world!';
const substring = message.substring(0, 5);
console.log(substring);

// Output: Hello

  • In this example, the substring() method is used to extract the characters from index 0 to index 5 (exclusive) from the message string, resulting in the substring 'Hello'

  • By omitting the second parameter, the substring() method will extract the characters from the starting index to the end of the string:

const message = 'Hello, world!';
const substring = message.substring(7);
console.log(substring);

// Output: world!

  • Here, the substring() method extracts the characters from index 7 to the end of the message string, resulting in the substring 'world!'

Examiner Tips and Tricks

  • JavaScript allows flexibility in choosing single or double quotes to define strings, as long as you maintain consistency within a string

  • There are many other things you can do with strings in JavaScript but these are the only ones you need to know before the exam

  • The exam might give you additional string functionality but if it does it will provide the code and explain it

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