All Basic About Strings in JavaScript
Strings are used to store text. They are used to represent a sequence of characters. Strings are written with quotes. You can use single or double quotes.
let name = "Ajay";
let message = 'Hello, Ajay!';
String Length​
The length property returns the length of a string (number of characters).
let name = "Ajay";
console.log(name.length); // 4
Escape Characters​
In JavaScript, you can use the backslash \ to escape quotes and other characters.
let message = 'It\'s a beautiful day!';
console.log(message); // It's a beautiful day!
The backslash \ is used to escape quotes and other characters in a string.
| Code | Output | Description |
|---|---|---|
\' | ' | Single quote |
\" | " | Double quote |
\\ | \ | Backslash |
\n | New line | |
\r | Carriage return | |
\t | Tab | |
\b | Backspace | |
\f | Form feed | |
\v | Vertical tab |
String Methods​
JavaScript has a number of built-in methods for working with strings.
toUpperCase()​
The toUpperCase() method converts a string to uppercase letters.
let name = "Ajay";
console.log(name.toUpperCase()); // AJAY
toLowerCase()​
The toLowerCase() method converts a string to lowercase letters.
let name = "AJAY";
console.log(name.toLowerCase()); // ajay
charAt()​
The charAt() method returns the character at a specified index (position) in a string.
let name = "Ajay";
console.log(name.charAt(0)); // A
console.log(name.charAt(1)); // j
indexOf()​
The indexOf() method returns the position of the first occurrence of a specified value in a string.
let message = 'Hello, Ajay!';
console.log(message.indexOf('Ajay')); // 7
lastIndexOf()​
The lastIndexOf() method returns the position of the last occurrence of a specified value in a string.
let message = 'Hello, Ajay!';
console.log(message.lastIndexOf('l')); // 3
includes()​
The includes() method returns true if a string contains a specified value, otherwise false.
let message = 'Hello, Ajay!';
console.log(message.includes('Ajay')); // true
console.log(message.includes('Ajayy')); // false
// Case sensitive
console.log(message.includes('ajay')); // false
startsWith()​
The startsWith() method returns true if a string starts with a specified value, otherwise false.
let message = 'Hello, Ajay!';
console.log(message.startsWith('Hello')); // true
console.log(message.startsWith('Ajay')); // false
endsWith()​
The endsWith() method returns true if a string ends with a specified value, otherwise false.
let message = 'Hello, Ajay!';
console.log(message.endsWith('Ajay!')); // true
console.log(message.endsWith('Hello')); // false
slice()​
The slice() method extracts a part of a string and returns the extracted part in a new string.
let message = 'Hello, Ajay!';
console.log(message.slice(7)); // Ajay!
console.log(message.slice(7, 11)); // Ajay
substring()​
The substring() method extracts the characters from a string, between two specified indices, and returns the new sub string.
let message = 'Hello, Ajay!';
console.log(message.substring(7)); // Ajay!
console.log(message.substring(7, 11)); // Ajay
substr()​
The substr() method extracts the characters from a string, beginning at a specified start position, and through the specified number of character.
let message = 'Hello, Ajay!';
console.log(message.substr(7)); // Ajay!
console.log(message.substr(7, 4)); // Ajay
replace()​
The replace() method replaces a specified value with another value in a string.
let message = 'Hello, Ajay!';
console.log(message.replace('Ajay', 'John')); // Hello, John!
split()​
The split() method splits a string into an array of substrings, and returns the new array.
let message = 'Hello, Ajay!';
console.log(message.split(' ')); // [ 'Hello,', 'Ajay!' ]
trim()​
The trim() method removes whitespace from both ends of a string.
let message = ' Hello, Ajay! ';
console.log(message.trim()); // Hello, Ajay!
concat()​
The concat() method joins two or more strings.
let name = "Ajay";
let message = 'Hello, ';
console.log(message.concat(name)); // Hello, Ajay
repeat()​
The repeat() method returns a new string with a specified number of copies of the string it was called on.
let name = "Ajay";
console.log(name.repeat(3)); // AjayAjayAjay
padStart()​
The padStart() method pads the current string with another string until the resulting string reaches the given length.
let name = "Ajay";
console.log(name.padStart(10, 'Hi ')); // Hi Hi Ajay
padEnd()​
The padEnd() method pads the current string with another string until the resulting string reaches the given length.
let name = "Ajay";
console.log(name.padEnd(10, ' Hi')); // Ajay Hi Hi
match()​
The match() method searches a string for a match against a regular expression, and returns the matches, as an Array object.
let message = 'Hello, Ajay!';
console.log(message.match('Ajay')); // [ 'Ajay', index: 7, input: 'Hello, Ajay!', groups: undefined ]
search()​
The search() method searches a string for a specified value, and returns the position of the match.
let message = 'Hello, Ajay!';
console.log(message.search('Ajay')); // 7
localeCompare()​
The localeCompare() method compares two strings in the current locale.
let name1 = "Ajay";
let name2 = "John";
console.log(name1.localeCompare(name2)); // -1
console.log(name2.localeCompare(name1)); // 1
console.log(name1.localeCompare(name1)); // 0
charCodeAt()​
The charCodeAt() method returns the Unicode of the character at a specified index in a string.
let name = "Ajay";
console.log(name.charCodeAt(0)); // 65
console.log(name.charCodeAt(1)); // 106
fromCharCode()​
The fromCharCode() method converts Unicode values to characters.
console.log(String.fromCharCode(65)); // A
console.log(String.fromCharCode(106)); // j
fromCodePoint()​
The fromCodePoint() method returns a string created by using the specified sequence of code points.
console.log(String.fromCodePoint(65)); // A
console.log(String.fromCodePoint(106)); // j
codePointAt()​
The codePointAt() method returns a non-negative integer that is the Unicode code point value.
let name = "Ajay";
console.log(name.codePointAt(0)); // 65
console.log(name.codePointAt(1)); // 106
normalize()​
The normalize() method returns the Unicode Normalization Form of a given string.
let name = "Ajay";
console.log(name.normalize()); // Ajay
includes()​
The includes() method determines whether a string contains the characters of a specified string.
let name = "Ajay";
console.log(name.includes('A')); // true
console.log(name.includes('a')); // false
Template Literals​
Template literals are string literals allowing embedded expressions. You can use multi-line strings and string interpolation features with them. They were called "template strings" in prior editions of the ES2015 specification.
let name = "Ajay";
let message = `Hello, ${name}!`;
console.log(message); // Hello, Ajay!
Template literals are enclosed by the back-tick (<) (grave accent) character instead of double or single quotes.
Conclusion​
In this tutorial, we learned about strings in JavaScript and various methods to work with strings. We also learned about template literals.