Strings

A string is a sequence of characters used to represent text. In JavaScript, any value placed between single or double quotes is considered a string. This means that 1 is a number, but "1" is a string. When used with strings, typeof returns the string "string":

> var s = "some characters";
> typeof s;
"string"
> var s = 'some characters and numbers 123 5.87';
> typeof s;
"string"

Here's an example of a number used in the string context:

> var s = '1';
> typeof s;
"string"

If you put nothing in quotes, it's still a string (an empty string):

> var s = ""; typeof s;
"string"

As you already know, when you use the plus sign with two numbers, this is the arithmetic addition operation. However, if you use the plus sign with strings, this is a string concatenation operation, and it returns the two strings glued together:

> var s1 = "web"; 
> var s2 = "site"; 
> var s = s1 + s2; 
> s;
"website"
> typeof s;
"string"

The dual purpose of the + operator is a source of errors. Therefore, if you intend to concatenate strings, it's always best to make sure that all of the operands are strings. The same applies for addition; if you intend to add numbers, make sure the operands are numbers. You'll learn various ways to do so further in the chapter and the book.

> var s = '1'; 
> s = 3 * s; 
> typeof s;
"number"
> s;
3
> var s = '1';
> s++;
> typeof s;
"number"
> s;
2

> var s = "100"; typeof s;
"string"
> s = s * 1;
100
> typeof s;
"number"

> var movie = '101 dalmatians';
> movie * 1;
NaN

> var n = 1;
> typeof n;
"number"
> n = "" + n;
"1"
> typeof n;
"string"

Special strings

There are also strings with special meanings, as listed in the following table:

There are also additional characters that are rarely used: \b (backspace), \v (vertical tab), and \f (form feed).