Set - 7

Question 11 :

eval()?

Answer :

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


Question 12 :

What does break and continue statements do?

Answer :

Continue statement continues the current loop (if label not specified) in a new iteration whereas break statement exits the current loop.


Question 13 :

How to create a function using function constructor? 

Answer :

The following example illustrates this
It creates a function called square with argument x and returns x multiplied by itself.
var square = new Function ("x","return x*x");


Question 14 :

What's Prototypes for JavaScript?

Answer :

Objects have "prototypes" from which they may inherit fields and functions.

<script type="text/javascript">
function movieToString() {
return("title: "+this.title+" director: "+this.director);
}
function movie(title, director) {
this.title = title;
this.director = director || "unknown"; //if null assign to "unknown"
this.toString = movieToString; //assign function to this method pointer
}
movie.prototype.isComedy = false; //add a field to the movie's prototype
var officeSpace = new movie("OfficeSpace");
var narnia = new movie("Narni","Andrew Adamson");
document.write(narnia.toString());
document.write("
Narnia a comedy? "+narnia.isComedy);
officeSpace.isComedy = true; //override the default just for this object
document.write("
Office Space a comedy? "+officeSpace.isComedy);
</script>


Question 15 :

unescape(), escape()

Answer :

These are similar to the decodeURI() and encodeURI(), but escape() is used for only portions of a URI.

<script type="text/javascript">
var myvalue = "Sir Walter Scott";
document.write("Original myvalue: "+myvalue);
document.write("<br />escaped: "+escape(myvalue));
document.write("<br />uri part: \"&author="+escape(myvalue)+"\"");
</script>

If you use escape() for the whole URI... well bad things happen.

<script type="text/javascript">
var uri = "http://www.google.com/search?q=sonofusion Taleyarkhan"
document.write("Original uri: "+uri);
document.write("
escaped: "+escape(uri));
</script>