Javascript String

The String type represents a sequence of 16-bit Unicode characters. Strings can be created by either double quotes (") or single quotes ('). The quotes must match(start with " end with ").

Both of the following are legal:

var firstName = "first";
var lastName = 'last';

A string beginning with a double quote must end with a double quote, and a string beginning with a single quote must end with a single quote.

For example, the following will cause a syntax error:

var firstName = 'a string";    //syntax error - quotes must match


var firstName = "first"; 
var lastName = 'last';
console.log(firstName);
console.log(lastName);

The code above generates the following result.

String Escape

To input non-inputable value we have to use escapes. The escapes start with a \.

Escape	Meanings
\n	New line
\t	Tab
\b	Backspace
\r	Carriage return
\f	Form feed
\\	Backslash (\)
\'	Escape single quote (')
\"	Escape double quote (")
\xnn	A character represented by hexadecimal code nn.
\unnnn	A Unicode character represented by the hexadecimal code nnnn.

These character literals can be included anywhere with a string and will be interpreted as if they were a single character.

var text = "This is the letter sigma: \u03a3.";

The string in the code above is 28 characters long even though the escape sequence is 6 characters long. The entire escape sequence represents a single character, so it is counted as 1.

The following code uses the escape sequence to input string values.


console.log("\"");
console.log('\'');
console.log('\x42');
console.log("\u03a3");

The code above generates the following result.

String length

The string length is the number of 16-bit characters in the string.

The length of any string can be returned by using the length property as follows:


var text = "This is a test.";
console.log(text.length);

The length of a string can be returned by using the length property:


var firstName = 'first';
console.log(firstName.length);

The code above generates the following result.