JavaScript Strings

JavaScript strings are used for storing and manipulating text.

JavaScript Strings

A JavaScript string is zero or more characters written inside quotes.

Example

var answer = “It’s alright”;
var answer = “He is called ‘Johnny'”;
var answer = ‘He is called “Johnny”‘;

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String Length

The length of a string is found in the built in property length:

Example

var txt = “ABCDEFGHIJKLMNOPQRSTUVWXYZ”;
var sln = txt.length;

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Special Characters

Because strings must be written within quotes, JavaScript will misunderstand this string:

var x = “We are the so-called “Vikings” from the north.”;

The string will be chopped to “We are the so-called “.

The solution to avoid this problem, is to use the backslash escape character.

The backslash (\) escape character turns special characters into string characters:

Code	Result	Description
\’	‘	Single quote
\”	“	Double quote
\\	\	Backslash

The sequence \” inserts a double quote in a string:

Example

var x = “We are the so-called \”Vikings\” from the north.”;

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The sequence \’ inserts a single quote in a string:

Six other escape sequences are valid in JavaScript:

Code	Result
\b	Backspace
\f	Form Feed
\n	New Line
\r	Carriage Return
\t	Horizontal Tabulator
\v	Vertical Tabulator

The 6 escape characters above were originally designed to control typewriters, teletypes, and fax machines. They do not make any sense in HTML.

Breaking Long Code Lines

For best readability, programmers often like to avoid code lines longer than 80 characters.

If a JavaScript statement does not fit on one line, the best place to break it is after an operator:

Example

document.getElementById(“demo”).innerHTML =
“Hello Dolly!”;

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You can also break up a code line within a text string with a single backslash:

Strings Can be Objects

Normally, JavaScript strings are primitive values, created from literals:

var firstName = “John”;

But strings can also be defined as objects with the keyword new:

var firstName = new String(“John”);

Example

var x = “John”;
var y = new String(“John”);

// typeof x will return string
// typeof y will return object

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Don’t create strings as objects. It slows down execution speed.
The new keyword complicates the code. This can produce some unexpected results:

When using the == operator, equal strings are equal:

Example

var x = “John”;
var y = new String(“John”);

// (x == y) is true because x and y have equal values.

JavaScript Strings