From http://www.w3schools.com (Copyright Refsnes Data)

JavaScript Special Characters

In JavaScript you can add special characters to a text string by using the backslash sign.

Insert Special Characters

The backslash (\) is used to insert apostrophes, new lines, quotes, and other special characters into a text string.

Look at the following JavaScript code:

var txt="We are the so-called "Vikings" from the north.";
document.write(txt);

In JavaScript, a string is started and stopped with either single or double quotes. This means that the string above will be chopped to: We are the so-called

To solve this problem, you must place a backslash (\) before each double quote in "Viking". This turns each double quote into a string literal:

var txt="We are the so-called \"Vikings\" from the north.";
document.write(txt);

JavaScript will now output the proper text string: We are the so-called "Vikings" from the north.

Here is another example:

document.write ("You \& I are singing!"); 

The example above will produce the following output:

You & I are singing!

The table below lists other special characters that can be added to a text string with the backslash sign:

From http://www.w3schools.com (Copyright Refsnes Data)