Strings

Anonymous contributor

Published Jul 30, 2021Updated Aug 17, 2024

Strings are a primitive data type. They are any grouping of characters (letters, spaces, numbers, or symbols) surrounded by single quotes ', double quotes " or backticks `.

Concatenation

In JavaScript, multiple strings can be concatenated or joined together using the + operator.

In the example below, multiple strings and variables containing string values have been concatenated. After the code block is run, the displayText variable will contain the concatenated string:

let service = 'credit card';
let month = 'May 30th';
let displayText = 'Your ' + service + ' bill is due on ' + month + '.';

console.log(displayText);
// Output: Your credit card bill is due on May 30th.

Interpolation

String interpolation is the process of evaluating string literals containing one or more placeholders (expressions, variables, etc). It can be performed using template literals (text ${expression} text), as in the following example:

let age = 7;

// String concatenation
console.log('Tommy is ' + age + ' years old.');
// Output: Tommy is 7 years old.

// String interpolation
console.log(`Tommy is ${age} years old.`);
// Output: Tommy is 7 years old.

Escaping Characters

On occasion, it may be necessary to include characters in a string that may have reserved meanings or to apply additional formatting. Characters, such as quotes, can be included by prepending a \. There are a number of predefined escape sequences such as \n or \t to add formatting such as a line break or tab respectively:

// Line break
console.log('Hello\nWorld');
// Output:
// Hello
// World

// Including quotes
console.log('"Wayne\'s World"');
// Output: "Wayne's World"

Codebyte Example

The following codebyte example demonstrates how the above concepts work:

us
Visit us
code
Hide code
Code
OutputHide output
Hide output
Loading...

Strings

.at(): Returns the character at a particular index in a string.
.charAt(): Returns a single character at the specified index of a string.
.charCodeAt(): Returns an integer representing the UTF-16 character code at the specified index in a string.
.concat(): Concatenates or combines strings together.
.includes(): Returns true if a given value is included in a string.
.indexOf(): Searches a string for a given value and returns the first index if found.
.length: Returns the number of characters in a string.
.padEnd(): Pads a string with a given string until the resulting string reaches the specified length.
.padStart(): Generates a new string of a specified length by adding a given padding string to the beginning of the original string.
.repeat(): Repeats a string a specified number of times. String will be concatenated.
.replace(): Searches a string for a string value, or a regular expression, and returns a new string where some or all matches are replaced.
.replaceAll(): Returns a new string by replacing all the matches of a given search value with a given replacement value.
.search(): Takes a regular expression argument and returns either the character position of the start of the first matching substring or -1 if there is no match.
.slice(): Returns a selected portion of a string.
.split(): Returns a new array of substrings based on a given string.
.startsWith(): Checks whether a string begins with the specified characters. It returns true if it does, otherwise false.
.substr(): Extracts a portion of a string beginning at a specified position and continues for a specified number of characters.
.substring(): Returns a part of a string from a given starting index or between the start and end index. The index starts at zero.
.toLowerCase(): Convert a string to lowercase letters.
.toString(): Returns a string representing the object.
.toUpperCase(): Converts the lowercase letters of a string to uppercase.
.trim(): Removes existing whitespace from both ends of a string.
.valueOf(): Returns the value of a String object as a string.