I understand that Node.js has the concept of event-driven, asynchronous
callbacks, by utilizing an event loop.
database.query("SELECT * FROM hugetable", function(rows) { var result =
rows; });
console.log("Hello World");
Here, instead of expecting *database.query()* to directly return a result
to us, we pass it a second parameter, an anonymous function.
Now, Node.js can handle the database request asynchronously. Provided that *
database.query()* is part of an asynchronous library, this is what Node.js
does: just as before, it takes the query and sends it to the database. But
instead of waiting for it to be finished, it makes a mental note that says
"When at some point in the future the database server is done and sends the
result of the query, then I have to execute the anonymous function that was
passed to *database.query()*."
I am trying the same with a sample code (as I am a newbie and not reached
till Node.js DB interactions):
[root@example]# cat server8.js
function myfun(noparm , afterend)
{
for ( var i =0; i < 10; i ++)
console.log("The valus is " + i);
}
function mynextfn()
{
console.log("Hello World");
}
function afterend()
{
console.log("Hello afterend");
}
myfun(0, afterend);
mynextfn();
[root@idc-bldtool01 example]# node server8.js
The valus is 0
The valus is 1
The valus is 2
The valus is 3
The valus is 4
The valus is 5
The valus is 6
The valus is 7
The valus is 8
The valus is 9
Hello World
[root@iexample]#
As such I do not see the " concept of event-driven, asynchronous callbacks,
by utilizing an event loop" ?
Can anyone please help me in implementing some basic examples?
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