How to have an element invoke a javascript on selection, instead of going to a new URL: ?
<script type="text/javascript">
function pseudoHitMe() {
alert("Ouch!");
}
</script>
<a href="javascript:pseudoHitMe()">hit me</a<pre>
How to have the status line update when the mouse goes over a link (The support of the status line is sporadic)?
<pre lang="javascript"><a href="javascript.shtml"
onmouseover="window.status=’Hi There!’;return true"
onmouseout="window.status=”;return true">Look at the Status bar</a>
Look at the [...]
How to getting values from cookies to set widgets?
function getCookieData(labelName) {
//from Danny Goodman
var labelLen = labelName.length;
// read cookie property only once for speed
var cookieData = document.cookie;
var cLen = cookieData.length;
var i = 0;
var cEnd;
while (i < cLen) {
var j = i + labelLen;
if (cookieData.substring(i,j) == labelName) {
cEnd = cookieData.indexOf(";",j);
if (cEnd == -1) {
cEnd = cookieData.length;
}
return unescape(cookieData.substring(j+1, [...]
eval()?
The eval() method is incredibly powerful allowing you to execute snippets of code during execution.
<script type="text/javascript">
var USA_Texas_Austin = "521,289";
document.write("Population is "+eval("USA_"+"Texas_"+"Austin"));
</script>
This produces
Population is 521,289
What does break and continue statements do?
Continue statement continues the current loop (if label not specified) in a new iteration whereas break statement exits the current loop.
How to create a function using [...]
How to create an object using JavaScript?
Objects can be created in many ways. One way is to create the object and add the fields directly.
var myMovie = new Object();
myMovie.title = “Aliens”;
myMovie.director = “James Cameron”;
document.write(”movie: title is \”"+myMovie.title+”\”");
How to use strings as array indexes using JavaScript?
Javascript does not have a true hashtable object, but through its wierdness, you can use the array as a hashtable.
<script type="text/javascript">
var days = ["Sunday","Monday","Tuesday","Wednesday", "Thursday","Friday","Saturday"];
for(var i=0; i < days.length; i++) {
days[days[i]] = days[i];
}
document.write("days[\"Monday\"]:"+days["Monday"]);
</script>
This produces
days["Monday"]:Monday
How to use “join()” to create a string from an array using JavaScript?
“join” concatenates [...]
What does the delete operator do?
The delete operator is used to delete all the variables and objects used in the program ,but it does not delete variables declared with var keywor
How tp create Arrays using JavaScript ?
<script type="text/javascript">
var days = new Array();
days[0] = "Sunday"
days[1] = "Monday"
days[2] = "Tuesday"
days[3] = "Wednesday"
days[4] = "Thursday"
days[5] = "Friday"
days[6] = [...]
How to Handle Event Handlers?
You can add an event handler in the HTML definition of the element like this,
<script type="text/javascript"><!–
function hitme() {
alert("I’ve been hit!");
}
// –>
</script>
<input type="button" id="hitme" name="hitme" value="hit me" onclick="hitme()"
Or, interestingly enough you can just assign the event’s name on the object directly with a reference to the method you want to assign.
<input type="button" [...]
How to find radio button selection when a form is submitted?
<script type="text/javascript">
function findButton() {
var myForm = document.forms.animalForm;
var i;
for(i=0;i<myForm.marsupial.length; i++) {
if(myForm.marsupial[i].checked) {
break;
}
}
alert("You selected \""+myForm.marsupial[i].value+"\".");
}
</script>
<form name="animalForm" action="">
<input type="radio" name="marsupial" value="kangaroo" />
Kangaroo
Opossum
Tasmanian Tiger
<input type="button" name="GO" value="GO" onclick="findButton()" />
How to disable an HTML object ?
document.getElementById(”myObject”).disabled = true;
To write messages to the screen without using “document.write()” ?
Changing the contents of [...]
What does undefined value mean in javascript?
Undefined value means the variable used in the code doesn’t exist or is not assigned any value or the property doesn’t exist.
What is the difference between undefined value and null value?
(i)Undefined value cannot be explicitly stated that is there is no keyword called undefined whereas null value has keyword [...]
What does the term sticky session mean in a web-farm scenario? Why would you use a sticky session? What is the potential disadvantage of using a sticky session?
Sticky session refers to the feature of many commercial load balancing solutions for web-farms to route the requests for a particular session to the same physical machine that [...]
