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String Methods in JavaScript

String Manipulation Methods​

eval()​

  • Description: Evaluates a string as JavaScript code.
  • Example:
    eval("3 - 2"); // 1
    eval(new String("3 - 2")); // "3 - 2" (no evaluation for string objects)

charAt()​

  • Description: Returns the character at the specified index.
  • Example:
    let str = "Hello";
    console.log(str.charAt(1)); // "e"
    console.log(str[1]); // "e"

codePointAt() (ES6)​

  • Description: Returns the Unicode code point value at the specified position.
  • Example:
    let str = "A";
    console.log(str.codePointAt(0)); // 65

String Comparison​

  • Description: Compare strings using <, >, = operators.
  • Example:
    "apple" < "banana"; // true

replace()​

  • Description: Replaces matched substrings with a new string.
  • Example:
    let str = "Hello world";
    console.log(str.replace("world", "JavaScript")); // "Hello JavaScript"

String.fromCharCode()​

  • Description: Returns a string created from the specified sequence of UTF-16 code units.
  • Example:
    console.log(String.fromCharCode(65)); // "A"

String.fromCodePoint() (ES6)​

  • Description: Returns a string created from the specified sequence of code points.
  • Example:
    console.log(String.fromCodePoint(9731)); // "☃"

concat()​

  • Description: Concatenates two or more strings.
  • Example:
    let str1 = "Hello";
    let str2 = "World";
    console.log(str1.concat(" ", str2)); // "Hello World"

includes() (ES6)​

  • Description: Checks if a string contains a specified substring.
  • Example:
    let str = "Hello world";
    console.log(str.includes("world")); // true

indexOf()​

  • Description: Returns the index of the first occurrence of a specified value.
  • Example:
    let str = "Hello world";
    console.log(str.indexOf("o")); // 4

lastIndexOf()​

  • Description: Returns the index of the last occurrence of a specified value.
  • Example:
    console.log(str.lastIndexOf("o")); // 7

String Matching and Searching​

match()​

  • Description: Matches a string against a regular expression.
  • Example:
    let str = "Hello world";
    console.log(str.match(/o/g)); // ["o", "o"]

matchAll() (ES6)​

  • Description: Returns all matches against a regular expression.
  • Example:
    for (let match of str.matchAll(/o/g)) {
      console.log(match);
    }

repeat() (ES6)​

  • Description: Repeats the string a specified number of times.
  • Example:
    let str = "Hello";
    console.log(str.repeat(3)); // "HelloHelloHello"
  • Description: Searches for a match against a regular expression.
  • Example:
    let str = "Hello world";
    console.log(str.search(/world/)); // 6

Substring Methods​

split()​

  • Description: Splits a string into an array of substrings.
  • Example:
    let str = "a,b,c";
    console.log(str.split(",")); // ["a", "b", "c"]

substr()​

  • Description: Extracts a substring based on a starting position and length.
  • Example:
    let str = "Hello world";
    console.log(str.substr(6, 5)); // "world"

substring()​

  • Description: Extracts a substring between two indices.
  • Example:
    console.log(str.substring(0, 5)); // "Hello"

slice()​

  • Description: Extracts a substring from a string (similar to substring()).
  • Example:
    console.log(str.slice(0, 5)); // "Hello"

Case Conversion​

toLowerCase(), toUpperCase()​

  • Description: Converts string to lowercase or uppercase.
  • Example:
    let str = "Hello";
    console.log(str.toLowerCase()); // "hello"
    console.log(str.toUpperCase()); // "HELLO"

toLocaleLowerCase(), toLocaleUpperCase()​

  • Description: Locale-sensitive case conversion.
  • Example:
    console.log(str.toLocaleLowerCase()); // "hello"
    console.log(str.toLocaleUpperCase()); // "HELLO"

Utility Methods​

toString()​

  • Description: Returns a string representation of the object.
  • Example:
    let num = 123;
    console.log(num.toString()); // "123"

trim()​

  • Description: Removes whitespace from both ends of the string.
  • Example:
    let str = "   Hello   ";
    console.log(str.trim()); // "Hello"

startsWith() (ES6)​

  • Description: Checks if a string starts with a specified value.
  • Example:
    let str = "Hello world";
    console.log(str.startsWith("Hello")); // true

endsWith() (ES6)​

  • Description: Checks if a string ends with a specified value.
  • Example:
    console.log(str.endsWith("world")); // true

normalize() (ES6)​

  • Description: Returns the Unicode normalization form of the string.
  • Example:
    let str = "\u1E9B\u0323";
    console.log(str.normalize("NFC")); // "\u1E9B\u0323" -> "\u1E9B\u0323"

raw() (ES6)​

  • Description: Returns the raw string representation of template literals.
  • Example:
    let str = String.raw`Hello\nWorld`;
    console.log(str); // "Hello\\nWorld"