JavaScript Strings

JavaScript strings are used for storing and manipulating text.
A string can be any text inside double or single quotes.

Strings can contain letters, numbers, symbols, punctuation, and even emoji.

A JavaScript string stores a series of characters like "Jonny Cash" or 'This is it'.

String indexes are zero-based: The first character is in position 0, the second in position 1 and so on.


Enclosing quotation marks

Strings are contained within a pair of either single quotation marks as 'a text' or double quotation marks as "a text".

Do you want to use quotation marks inside a string? Then use the opposite quotation marks inside and outside. Strings containing single quotes need to use double quotes and strings containing double quotes need to use single quotes.

JS JavaScript - Enclosing quotation marks

// String containing a single quotes
"It's eight o'clock.";
 
// String containing double quotes
'Remember to say "please" and "thank you."';

Is is also possible to use a backslash \ to escape the quotation marks. This lets JavaScript know in advance that you want to use a special character.


// Escaping special characters with \
'It\'s eight o\'clock.';
"Remember to say \"please\" and \"thank you.\"";

Long literal strings

Strings can sometimes be very long and go on endlessly. You should then break the string into multiple lines without affecting the actual string content.

Use the + operator to append multiple strings.

JS JavaScript - Long literal strings

// A long string wrapped on multiple lines
var longString = "This is a very long string that I would like" +
"to wrap into multiple lines to make my code " +
"more readable.";

It is also possible to use the backslash character ("\") at the end of each line to indicate that the string will continue on the next line. Make sure there is no space or any other character after the backslash (except for a line break), or as an indent; otherwise it will not work.


// A long string wrapped on multiple lines
var longString = "This is a very long string that I would like \
to wrap into multiple lines to make my code \
more readable.";

String Properties and methods

Here are some of the most common String properties and methods.

Property/
Method
Description Example Output
length Property that returns number of characters. "horse".length; 5
trim Trim method returns a copy of the string with beginning and ending whitespace characters removed. "   keep spaces in the middle    ".trim(); "keep spaces in the middle"
toLowerCase ToLowerCase method returns a copy of the string with its letters converted to lowercase. Numbers, symbols, and other characters are not affected. "High and Low ".toLowerCase(); "high and low"
toUpperCase ToUpperCase method returns a copy of the string with its letters converted to capitals. Numbers, symbols, and other characters are not affected. "High and Low".toUpperCase(); "HIGH AND LOW"

 


Learn more about JavaScript String Methods

Comparing strings

You can compare strings using the less-than and greater-than operators. You may also use the localeCompare() method inherited by String instances.

JS JavaScript - Comparing strings

<!DOCTYPE html><html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
  <title>Comparing strings</title>
</head>
<body>
<h1>Compare strings</h1>
<p>Press the button to compare 'a' and 'b'.</p><button onclick="testStringCompare()">Click me to test</button><script>
        function testStringCompare() 
        { 
            var a = 'a';
            var b = 'b';
 
            if (a < b ) { // true
              alert ( a + ' is less than ' + b );
            } else if (a > b) {
              alert(a + ' is greater than ' + b);
            } else {
              alert(a + ' and ' + b + ' are equal.');
            }
        }
</script>
</body>
</html>

Escape sequences

Escape sequences that are valid in JavaScript.

Code

Result

\b

Backspace

\f

Form Feed

\n

New Line

\r

Carriage Return

\t

Horizontal Tabulator

\v

Vertical Tabulator

\\

backslash

\"

double quote

\'

single quote

\XXX

an octal Latin-1 character

\uXXXX

unicode codepoint

\u{X} ... \u{XXXXXX}

unicode codepoint

\xXX

the Latin-1 character


Learn more about JavaScript Assignment Learn more about JavaScript Comments
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JavaScript is one of the 3 core language technologies of the World Wide Web that all web developers must learn:

1.      HTML to define the content of web pages.

2.      CSS to specify the layout of web pages.

3.      JavaScript to program the behavior of web pages.

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The benefits of using JavaScript are:

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