String Methods

STRING_METHODS.md

String Methods Cheatsheet

Table of Contents

• String Length
• Case Conversion
• Substring Extraction
• String Manipulation
• String Formatting
• Template Literal (ES6)

String Length

• str.length: Returns the length of the string.

Case Conversion

• str.toUpperCase(): Converts the string to uppercase.

  • Parameters: None.
  • Example:

    const str = 'hello';
    console.log(str.toUpperCase()); // Output: HELLO

• str.toLowerCase(): Converts the string to lowercase.

  • Parameters: None.
  • Example:

    const str = 'WORLD';
    console.log(str.toLowerCase()); // Output: world

Substring Extraction

• str.slice(startIndex, endIndex): Extracts a portion of the string from startIndex to endIndex (exclusive).

  • Parameters:
    • startIndex: The starting index of the substring (inclusive).
    • endIndex (optional): The ending index of the substring (exclusive).
  • Example:

    const str = 'Hello, World!';
    console.log(str.slice(7, 12)); // Output: World

• str.substring(startIndex, endIndex): Extracts a portion of the string from startIndex to endIndex (exclusive), but treats negative indices as 0.

  • Parameters:
    • startIndex: The starting index of the substring (inclusive).
    • endIndex (optional): The ending index of the substring (exclusive).
  • Example:

    const str = 'Hello, World!';
    console.log(str.substring(7, 12)); // Output: World

• str.substr(startIndex, length): Extracts a portion of the string starting from startIndex with the specified length.

  • Parameters:
    • startIndex: The starting index of the substring (inclusive).
    • length (optional): The length of the substring.
  • Example:

    const str = 'Hello, World!';
    console.log(str.substr(7, 5)); // Output: World

String Manipulation

• str.concat(str2, str3, ..., strN): Concatenates one or more strings with the original string.

  • Parameters:
    • str2, str3, ..., strN (optional): Strings to concatenate.
  • Example:

    const str1 = 'Hello';
    const str2 = 'World';
    console.log(str1.concat(', ', str2)); // Output: Hello, World

• str.replace(searchValue, replaceValue): Replaces occurrences of searchValue with replaceValue.

  • Parameters:
    • searchValue: The value to search for.
    • replaceValue: The value to replace occurrences of searchValue.
  • Example:

    const str = 'Hello, World!';
    console.log(str.replace('World', 'John')); // Output: Hello, John!

• str.trim(): Removes leading and trailing whitespace from the string.

  • Parameters: None.
  • Example:

    const str = '   Hello, World!   ';
    console.log(str.trim()); // Output: Hello, World!

• str.split(separator): Splits the string into an array of substrings based on the separator character.

  • Parameters:
    • separator: The character or substring used to determine where to split the string.
  • Example:

    const str = 'Hello,World,!';
    console.log(str.split(',')); // Output: ['Hello', 'World', '!']

• str.charAt(index): Returns the character at the specified index.

  • Parameters:
    • index: The index of the character to retrieve.
  • Example:

    const str = 'Hello, World!';
    console.log(str.charAt(7)); // Output: W

• str.charCodeAt(index): Returns the Unicode value of the character at the specified index.

  • Parameters:
    • index: The index of the character.
  • Example:

    const str = 'Hello, World!';
    console.log(str.charCodeAt(7)); // Output: 87

• str.indexOf(searchValue, startIndex): Returns the index of the first occurrence of searchValue starting from startIndex.

  • Parameters:
    • searchValue: The value to search for.
    • startIndex (optional): The index to start searching from.
  • Example:

    const str = 'Hello, World!';
    console.log(str.indexOf('o')); // Output: 4

• str.lastIndexOf(searchValue, startIndex): Returns the index of the last occurrence of searchValue starting from startIndex.

  • Parameters:
    • searchValue: The value to search for.
    • startIndex (optional): The index to start searching from.
  • Example:

    const str = 'Hello, World!';
    console.log(str.lastIndexOf('o')); // Output: 8

• str.startsWith(searchValue): Checks if the string starts with searchValue.

  • Parameters:
    • searchValue: The value to search for.
  • Example:

    const str = 'Hello, World!';
    console.log(str.startsWith('Hello')); // Output: true

• str.endsWith(searchValue): Checks if the string ends with searchValue.

  • Parameters:
    • searchValue: The value to search for.
  • Example:

    const str = 'Hello, World!';
    console.log(str.endsWith('World!')); // Output: true

• str.includes(searchValue): Checks if the string contains searchValue.

  • Parameters:
    • searchValue: The value to search for.
  • Example:

    const str = 'Hello, World!';
    console.log(str.includes('World')); // Output: true

String Formatting

• str.padStart(targetLength, padString): Pads the string from the start with padString until it reaches the targetLength.

  • Parameters:
    • targetLength: The length the string should reach.
    • padString (optional): The string to pad with (default is a space).
  • Example:

    const str = 'Hello';
    console.log(str.padStart(10, 'X')); // Output: XXXXHello

• str.padEnd(targetLength, padString): Pads the string from the end with padString until it reaches the targetLength.

  • Parameters:
    • targetLength: The length the string should reach.
    • padString (optional): The string to pad with (default is a space).
  • Example:

    const str = 'Hello';
    console.log(str.padEnd(10, 'X')); // Output: HelloXXXX

• str.repeat(count): Repeats the string count number of times.

  • Parameters:
    • count: The number of times to repeat the string.
  • Example:

    const str = 'Hello';
    console.log(str.repeat(3)); // Output: HelloHelloHello

Template Literal (ES6)

• ${variable}: Interpolates the value of variable within a string.
• Multiline strings: Enclose multiline strings using backticks (`).

For more detailed information and additional string methods, please refer to the documentation of the programming language or framework you are using.