Speaking JavaScript

Chapter 12. Strings

Strings are immutable sequences of JavaScript characters. Each such character is a 16-bit UTF-16 code unit. That means that a single Unicode character is represented by either one or two JavaScript characters. You mainly need to worry about the two-character case whenever you are counting characters or splitting strings (see Chapter 24).

String Literals

Both single and double quotes can be used to delimit string literals:

'He said: "Hello"'
"He said: \"Hello\""

'Everyone\'s a winner'
"Everyone's a winner"

Thus, you are free to use either kind of quote. There are several considerations, though:

• The most common style in the community is to use double quotes for HTML and single quotes for JavaScript.
• On the other hand, double quotes are used exclusively for strings in some languages (e.g., C and Java). Therefore, it may make sense to use them in a multilanguage code base.
• For JSON (discussed in Chapter 22), you must use double quotes.

Your code will look cleaner if you quote consistently. But sometimes, a different quote means that you don’t have to escape, which can justify your being less consistent (e.g., you may normally use single quotes, but temporarily switch to double quotes to write the last one of the preceding examples).

Escaping in String Literals

Most characters in string literals simply represent themselves. The backslash is used for escaping and enables several special features:

Line continuations

You can spread a string over multiple lines by escaping ...