Java Reference
In-Depth Information
trY it out
Checking a Character's Case
This is an example that detects the type of the character at the start of a given string—that is, whether
the character is uppercase, lowercase, numeric, or other:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Chapter 5, Example 2</title>
</head>
<body>
<script>
function checkCharType(charToCheck) {
var returnValue = "O";
var charCode = charToCheck.charCodeAt(0);
if (charCode >= "A".charCodeAt(0) && charCode <= "Z".charCodeAt(0)) {
returnValue = "U";
} else if (charCode >= "a".charCodeAt(0) &&
charCode <= "z".charCodeAt(0)) {
returnValue = "L";
} else if (charCode >= "0".charCodeAt(0) &&
charCode <= "9".charCodeAt(0)) {
returnValue = "N";
}
return returnValue;
}
var myString = prompt("Enter some text", "Hello World!");
switch (checkCharType(myString)) {
case "U":
document.write("First character was upper case");
break;
case "L":
document.write("First character was lower case");
break;
case "N":
document.write("First character was a number");
break;
default:
document.write("First character was not a character or a number");
}
</script>
</body>
</html>
Type the code and save it as
ch5_example2.html
. When you load the page into your browser, you will
be prompted for a string. A message will then be written to the page informing you of the type of the
first character that you entered—whether it is uppercase, lowercase, a number, or something else, such
as a punctuation mark.
