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Now that we have the browser name and its major version number, we need to match
up the names and numbers. This is done with if statements. Example 6-2 shows an if statement
that detects the presence of Netscape 6 using the browserName and browserVersion
variables defined in Example 6-1.
if (browserName == "Netscape" && browserVersion == 5) {
document.write("This is Netscape 6");
}
else {
document.write("This is not Netscape 6");
}Example 6-2: Checking for Netscape 6 and printing the results
This if statement compares both the browser's name and version: if the browser name is "Netscape" and the version is 5, it must be Netscape 6, so the code within the curly braces after the if is run, printing "This is Netscape 6" to the page. If the browser is not Netscape 6, the code in the curly braces following the else is run, printing "This is not Netscape 6".
| By combining a series of if statements, we can detect any browser that supports JavaScript. | |
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By combining a series of if statements similar to the one in Example 6-2, we can detect
any browser that supports JavaScript. Example 6-3 shows how to use if statements to piece together
the identity of the browser. This script detects the latest two versions of Navigator and the latest
four versions of Internet Explorer.
var browser;
if (browserName == "Netscape" && browserVersion == 5) {
browser = "nn6"; // Netscape 6
}
else if (browserName == "Netscape" && browserVersion == 4) {
browser = "nn4"; // Navigator 4
}
else if (browserName == "Microsoft Internet Explorer" &&
browserVersion == 4 &&
navigator.appVersion.indexOf("MSIE 6.0") != -1) {
browser = "ie6"; // IE 6.0
}
else if (browserName == "Microsoft Internet Explorer" &&
browserVersion == 4 &&
navigator.appVersion.indexOf("MSIE 5.5") != -1) {
browser = "ie55"; // IE 5.5
}
else if (browserName == "Microsoft Internet Explorer" &&
browserVersion == 4 &&
navigator.appVersion.indexOf("MSIE 5.0") != -1) {
browser = "ie5"; // IE 5.0
}
else if (browserName == "Microsoft Internet Explorer"
&& browserVersion == 4) {
browser = "ie4"; // IE 4
}Example 6-3: Detecting recent browsers from Netscape and Microsoft
| Detecting the different versions of Internet Explorer is complicated, because IE 4, IE 5, IE 5.5, and IE 6 all report a browser version of 4. | |
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Based on the browser's name and version, this script sets the variable browser to one
of six strings: "nn6", "nn4", "ie6", "ie55", "ie5", or "ie4", corresponding to Netscape Navigator
6 and 4 and Internet Explorer 6, 5.5, 5, and 4, respectively. Detecting the different versions of
IE is more complicated than detecting different versions of Navigator, because IE 4, IE 5, IE 5.5,
and IE 6 all report a browser version of 4. Thus, we have to use indexOf() to detect
the "MSIE #.#" portion of appVersion in order to distinguish among these browsers.
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Created: December 12, 2001
Revised: December 12, 2001
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