JavaScript String Methods
JavaScript provides a rich set of built-in methods for working with strings
Basic String Methods
- charAt(index):
- charCodeAt(index):
- concat(string1, string2, ...):
- indexOf(searchValue, startIndex)::
- lastIndexOf(searchValue, startIndex):
- slice(startIndex, endIndex):
- substring(startIndex, endIndex):
- substr(startIndex, length):
- toUpperCase():
- toLowerCase():
- trim():
- replace(searchValue, newValue):
Basic String Methods
: Returns the character at the specified index.
Example
const str = "Hello"; console.log(str.charAt(0)); // Output: "H"
charCodeAt(index):
: Returns the Unicode value of the character at the specified index.Example
const str = "Hello"; console.log(str.charCodeAt(0)); // Output: 72
concat(string1, string2, ...)
: Combines two or more strings and returns a new string.Example
const str1 = "Hello";
const str2 = "World";
console.log(str1.concat(" ", str2)); // Output: "Hello World"
indexOf(searchValue, startIndex)
: Returns the index of the first occurrence of a specified value within the string, starting the search at the optional startIndex.
Example
const str = "Hello World";
console.log(str.indexOf("World")); // Output: 6
lastIndexOf(searchValue, startIndex):
Returns the index of the last occurrence of a specified value within the string, starting the search at the optional startIndex.Example
const str = "Hello World";
console.log(str.lastIndexOf("o")); // Output: 7
slice(startIndex, endIndex):
Extracts a section of the string and returns it as a new string, starting from startIndex up to, but not including, endIndex.Example
const str = "Hello World"; console.log(str.slice(6)); // Output: "World"
substring(startIndex, endIndex):
Similar to slice(), but does not support negative indices. It extracts characters between startIndex and endIndex (not including endIndex).Example
const str = "Hello World"; console.log(str.substring(6, 11)); // Output: "World"
substr(startIndex, length):
Extracts a specified number of characters from the string, starting from startIndex, and returns them as a new string.Example
const str = "Hello World"; console.log(str.substr(6, 5)); // Output: "World"
toUpperCase():
Converts the string to uppercase.Example
const str = "hello"; console.log(str.toUpperCase()); // Output: "HELLO"
toLowerCase():
Converts the string to lowercase.Example
const str = "HELLO"; console.log(str.toLowerCase()); // Output: "hello"
trim():
Removes whitespace from both ends of the string.Example
const str = " Hello World "; console.log(str.trim()); // Output: "Hello World"