Computer Science AS OCR
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1-1-structure-and-function-of-the-processor as5 主题
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1-2-types-of-processor as3 主题
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1-3-input-output-and-storage as2 主题
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2-1-systems-software as8 主题
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2-3-software-development as5 主题
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2-4-types-of-programming-language as4 主题
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3-1-compression-encryption-and-hashing as3 主题
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3-2-databases as3 主题
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3-3-networks as8 主题
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3-4-web-technologies as13 主题
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html as
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css as
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css-styling as
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javascript as
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variables-and-constants-in-javascript as
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outputs-in-javascript as
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selection-in-javascript- as
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for-loops-in-javascript- as
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while-loops-in-javascript- as
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strings-in-javascript- as
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operators-in-javascript- as
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nested-statements-in-javascript as
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functions-and-procedures-in-javascript as
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html as
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4-1-data-types as8 主题
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4-2-data-structures as4 主题
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4-3-boolean-algebra as1 主题
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5-1-computing-related-legislation as4 主题
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5-2-moral-and-ethical-issues as9 主题
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6-1-thinking-abstractly as3 主题
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6-2-thinking-ahead as1 主题
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6-3-thinking-procedurally as3 主题
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6-4-thinking-logically as2 主题
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6-5-thinking-concurrently as2 主题
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7-1-programming-techniques as9 主题
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8-1-standard-algorithms-and-big-o-notation as8 主题
strings-in-javascript- as
Exam code:H046
Strings in JavaScript
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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
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Strings can be created in JavaScript by enclosing text within quotes:
const message = 'Hello, world!';const name = "John Doe";
String length
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To find the length of a string, use the
lengthproperty -
The
lengthproperty returns the number of characters in a string:
const message = 'Hello, world!';console.log(message.length);
// Output: 13
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In this example, the
lengthproperty is used to determine the number of characters in themessagestring
Substring extraction
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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
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In this example, the
substring()method is used to extract the characters from index 0 to index 5 (exclusive) from themessagestring, 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!
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Here, the
substring()method extracts the characters from index 7 to the end of themessagestring, resulting in the substring'world!'
Examiner Tips and Tricks
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JavaScript allows flexibility in choosing single or double quotes to define strings, as long as you maintain consistency within a string
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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
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The exam might give you additional string functionality but if it does it will provide the code and explain it
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