HTML and CSS Reference
In-Depth Information
The escape sequences will work only if in a <pre> tag or an alert dialog box.
The JavaScript program starts here.
The write() method sends to the browser a string containing two tabs (\ t\t ), Hello ,
a newline ( \n ) , world!, and another newline ( \n ).
The writeln() method sends to the browser a string containing a double quote ( \” ),
Nice day, Mate. , another double quote ( \” ), and a newline ( \n ). Because the
writeln() method automatically creates a newline, the output will display two
newlines: the default value and the \n in the string.
This string contains a backslash sequence that will be translated into Unicode.
The Unicode hexadecimal character 263a is preceded by a \u . The output is a smi-
ley face. See Figure 3.1.
Figure 3.1 Escape sequences.
Putting Strings Together. The process of joining strings together is called concate-
nation. The string concatenation operator is a plus sign (+). Its operands are two strings.
If one string is a number and the other is a string, JavaScript will still concatenate them
as strings. If both operands are numbers, the + will be the addition operator. The follow-
ing examples output “popcorn” and “Route 66” , respectively.
document.write("pop" + "corn");
document.write("Route " + 66);
The expression 5 + 100 results in 105 , whereas “ 5 + 100 results in “ 5100 ”.
Boolean Literals. Boolean literals are logical values that have only one of two values,
true or false . You can think of the values as yes or no, on or off, or 1 or 0. They are used
to test whether a condition is true or false. When using numeric comparison and equal-
ity operators, the value true evaluates to 1 and false evaluates to 0. (Read about compar-
ison operators in Chapter 5, “Operators.”)
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