Java Script Objects Class 4

7/31/2019 Java Script Objects Class 4

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JAVA SCRIPT OBJECTS(CONTD..)


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JavaScript Browser Detection

The Navigator object contains information

about the visitor's browser, such as visitor's

browser name, version, and more.

appNameholds the name of the browser

appVersionholds, among other things, the

version of the browser. To pull the version number

out of the string, we are using a function called

parseFloat(), which pulls the first thing that looks likea decimal number out of a string and returns it.


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EX 1:

var browser=navigator.appName;

var b_version=navigator.appVersion;var version=parseFloat(b_version);

document.write("Browser name: "+ browser);

document.write("
");

document.write("Browser version: "+ version);


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EX 2:

var x = navigator;

document.write("CodeName=" + x.appCodeName);

document.write("
");

document.write("MinorVersion=" + x.appMinorVersion);

document.write("
");

document.write("Name=" + x.appName);

document.write("
");

document.write("Version=" + x.appVersion);

document.write("
");

document.write("CookieEnabled=" + x.cookieEnabled);document.write("
");

document.write("CPUClass=" + x.cpuClass);

document.write("
");


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document.write("OnLine=" + x.onLine);

document.write("
");

document.write("Platform=" + x.platform);

document.write("
");

document.write("UA=" + x.userAgent);

document.write("
");

document.write("BrowserLanguage=" + x.browserLanguage);

document.write("
");

document.write("SystemLanguage=" + x.systemLanguage);

document.write("
");

document.write("UserLanguage=" + x.userLanguage);


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JavaScript Form Validation

Required Fields: The following functionchecks whether a required field has been left

empty. If the required field is blank, an alert is

displayed, and the function returns false. If avalue is entered, the function returns true

(means that data is OK):


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function validate_required(field,alerttxt)

{

with (field)

{

if (value==null||value==)

{

alert(alerttxt);return false; }else

{

return true; } } }


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function validate_form(thisform)

{

with (thisform)

{

if (validate_required(email,Email must be filledout!)==false)

{email.focus();return false;}

}

}


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Email:


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function validateForm()

{

var x=document.forms["myForm"]["fname"].value;

if (x==null || x=="")

{

alert("First name must be filled out");return false;

}

}


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First name:


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E-mail Validation

function validate_email(field,alerttxt)

{

with (field)

{

apos=value.indexOf(@);

dotpos=value.lastIndexOf(.);

if (apos


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function validate_form(thisform)

{

with (thisform)

{

if (validate_email(email,Not a valid e-mail

address!)==false)

{email.focus();return false;}

}

}


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Email:


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function validateForm()

{var x=document.forms["myForm"]["email"].value;

var atpos=x.indexOf("@");

var dotpos=x.lastIndexOf(".");

if (atpos


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Email:


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JavaScript Timing Events

setTimeout()Executes a code some time in thefuture

clearTimeout()Cancels the setTimeout()

The setTimeout() and clearTimeout() are both

methods of the HTML DOM Window object. setInterval() - executes a function, over and over

again, at specified time intervals.

The clearInterval() method is used to stop further

executions of the function specified in thesetInterval() method.

myVar=setInterval("javascriptfunction",milliseconds);

clearInterval(intervalVariable);


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function timedMsg()

{

var t=setTimeout("alert('I am displayed after 3 seconds!')",3000);}


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var c=0;

var t;var timer_is_on=0;

function timedCount()

{

document.getElementById('txt').value=c;

c=c+1;

t=setTimeout("timedCount()",1000);

}


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function doTimer()

{

if (!timer_is_on)

{

timer_is_on=1;

timedCount();

}

}


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Click on the button above. The input field willcount forever, starting at 0.


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Clearing Time out value

The syntax is as follows: clearTimeout(setTimeout_variable)

Ex:

var c=0;

var t;

var timer_is_on=0;

function timedCount()

{document.getElementById('txt').value=c;

c=c+1;

t=setTimeout("timedCount()",1000);

}


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function doTimer(){

if (!timer_is_on)

{

timer_is_on=1;

timedCount();}

}

function stopCount()

{

clearTimeout(t);timer_is_on=0;

}


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Click on the "Start count!" button above to start the timer. Theinput field will count forever, starting at 0. Click on the "Stop

count!" button to stop the counting. Click on the "Start count!"button to start the timer again.


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Click the first button to display the current time, and thesecond button to stop the time.

Try itStop time

var myVar;

function myFunction()

{

myVar=setInterval(function(){myTimer()},1000);

}


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function myTimer()

{

var d=new Date();

var t=d.toLocaleTimeString();

document.getElementById("demo").innerHTML=t;

}function myStopFunction()

{

clearInterval(myVar);

}

Java Script Objects Class 4

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