Strings - JavaScript

Summary

In JavaScript, strings can be wrapped in single quotes or double quotes.

const singleQuoteString = 'This is a string wrapped in double quotes';
const doubleQuoteString = "This is a string wrapped in double quotes";

Details

A string is a type of value in JavaScript. You can think of a string as any text wrapped in quotes. The text can be wrapped in single quotes or double quotes. A string can be a single character, a word, a sentence, or any combination of letters, symbols and numbers, as long as it is wrapped in quotes.

// These are all strings
const character = 'a';
const word = 'hello';
const sentence = 'Hello world!';
const symbols = '!@#$';
const numberString = '1';

Note that a number wrapped in quotes is considered a string by the computer, and is not the same as a number that is not wrapped in quotes. There are some instances where they can be used interchangably, but as a general rule you should think of them as being different.

// These values look similar, but are different types
const numberString = '1';
const number = 1;

Mixing quotes

If a string contains one or more single quotes (like an apostrophe), you should wrap it in double quotes to avoid errors. If you use single quotes in that situation, the computer will think the string ends early. Likewise, if a string contains double quotes, you should wrap it in single quotes to avoid errors.

// Mixing quotes
const singleQuoteString1 = 'This "string" is cool';
const doubleQuoteString1 = "I should've known";

Escaping quotes

Alternatively, you can escape the single quote or double quote character using a backslash (like \' or \").

// Escaping quotation marks
const singleQuoteString2 = 'I should\'ve known';
const doubleQuoteString2 = "This \"string\" is cool";

Combining strings

To concatenate (or combine) strings, you can use the plus sign:

// Concatenate string literals
const newString = "Hello " + "world";
// newString now equals "Hello world"

// Concatenate strings using variables
const firstString = "Hello ";
const secondString = "world";
const firstPlusSecondString = firstString + secondString;
// firstPlusSecondString now equals "Hello world"

If you try to combine two strings that contain numbers, the strings are combined, instead of added together.

const numberString = '1' + '1';
// numberString now equals '11', not '2' or 2

If you try to add a number to a string, the number is converted into a string and the strings are combined.

const numberString = '1' + 1;
// numberString now equals '11', not '2' or 2
const otherExample = 'hello' + 1;
// otherExample now equals 'hello1'

If you have a string stored inside a variable, you can also combine it with another string using the += operator, like this:

let greeting = 'hello';
greeting += ' world';
// greeting = 'hello world'

The += operator takes the string on the right, adds it to the string inside the variable, and stores the new value inside the same variable.

Demo

Exercises

Try the following statements in the console:

'String in single quotes'

"String in double quotes"

'This "string" is cool'

"I should've known"

'I should\'ve known'

"This \"string\" is cool"

"Hello " + "world"

'1' + '1'

'1' + 1

const firstString = "Hello ";
const secondString = "world";
const firstPlusSecondString = firstString + secondString;

References

String literals on MDN

Strings – JavaScript