03. Strings

Declaring Strings

You can use either double or single quotes to declare a string.

"Hello world!"   // declaring with double quotes
'Hello world!'                 // with single quotes
'She said, "she said"'         // Using double quotes within single quotes
"She said, \"Hello darling\""  // Escaping quotes with a backslash

As you can see in the above example, you can use the backslash key \" to escape the quote.

Escape characters

JavaScript provides a list of other escape characters as well.

\b
Backspace
\f
Form feed
\n
Newline
\r
Carriage Return
\t
Tab
\v
Vertical tab
\\
Backslash
document.write("\tHello\nWorld!");
//     Hello
// World!

String concatenation

To concatenate two strings together simply use the + operator.
var greeting = "Hello" + "world!";

Mixing numbers and strings

When adding numbers and strings together, you will get a string back, with the two values concatenated.

var cost = '8' + 9;   // cost = '89';

String properties and methods

The String object comes with a number of member attributes.

length
Number of characters in string.
substring(m)
Substring from m to the end.
substring(m,n)
Substring from m to but not including n.
toUpperCase()
Changes all casing to upper case.
toLowerCase()
Changes all casing to lower case.
trim()
Takes away whitespace away from both ends of a Stirng.
var sample = "Hello there."
sample.length;          // 12 characters
sample.substring(0,5);  // "Hello"
sample.toUpperCase();   // "HELLO THERE."

Capturing user input

To get input from your user, use the prompt() method. This will display a dialog box to the user, displaying the string passed in as an parameter to prompt().

var age = prompt("How old are you?");
// User is prompt for his age, which then gets placed in the age variable.
console.log(age); // outputs user's inputted age to the javascript console.

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