Paasing values to javascript from asp.net

[Priya]

Hey all,

I have some values in the database which has to retrieved and then
passed on to some functions in the javascript. The javascript file is
a separate file. I have included it in the aspx page using the src
option. How do I pass the values that I get from the database to
javascript ? Any help would be appreciated.

 

[Mark Rae]

I have some values in the database which has to retrieved and then
passed on to some functions in the javascript. The javascript file is
a separate file. I have included it in the aspx page using the src
option. How do I pass the values that I get from the database to
javascript ? Any help would be appreciated.

1) Store the values in hidden fields

or

2) Build up your JavaScript calls dynamically so that you can plug in the
correct parameter values

 

[Kevin Spencer]

Remember that JavaScript is just that: script. It is text. Database data is
not text. So, the first thing you need to do is to make sure that you
convert the data to the appropriate scripting text. Second, JavaScript is
scoped to a single HTML document instance, so if your Page is going to
PostBack, you will need to persist the data by passing it back and forth in
the Request, via hidden form fields, ViewState, or server-side state
persistence.

If your JavaScript is in a separate file, you will need to insert a script
into the Page that declares some variables or passes the scripted data to
functions in the external scripting file.

--
HTH,

Kevin Spencer
Microsoft MVP
Software Composer
http://unclechutney.blogspot.com

The shortest distance between 2 points is a curve.

 

[Eliyahu Goldin]

This may help you too:

http://usableasp.net/DeveloperPage....o/HowToPassMessagesBetweenServerAndClient.htm

--
Eliyahu Goldin,
Software Developer & Consultant
Microsoft MVP [ASP.NET]
http://msmvps.com/blogs/egoldin
http://usableasp.net

 

[Todd Gill]

You should keep in mind at what point the server code is executed by
the server (asp.net), and at what point the javascript code is
executed by the user's browser (javscript).

There are many ways to get your retrieved database values to your
javascript code. If you can include the javascript code on the
ASP.NET page you're using, it can work like this:

1. Update the javascript code when ASP.NET renders the page

<script language="javascript">

function myFunctionToRunAfterDB()
{
//Use ASP.NET to place your value into javascript code
var dbResultString = <%= strDBResult %>;
}

</script>

In this case, of course strDBResult is a public string for this
ASP.NET page.

2. Pass parameters to the javascript function defined in the
static .js file

If the javascript function you are using is in a static file (such as
myScript.js), a similar method may work as long as the javascript
function accepts parameters for the functions you wish to call (or the
javascript function otherwise has scope):

from myScript.js:
....
function myFunction(strToPrint)
{
alert(strToPrint);
}


from your asp.net page:

....
<script src="myScript.js" language="javascript"></script>
....
<script language="javascript">
//call the function, but pass in the newly-retrieved value
from ASP.NET
// this can also be called from any Javscript event such as
a button's "onClick" event
myFunction(<%= strDBResult %>);
</script>


3. Convert the .js file to an ASP.NET page

In some cases, it may be appropriate to convert your .js file into
a .aspx file. The file would still contain javascript code, but data
from ASP.NET can be added using the same technique I described in item
#1.

I've used all three methods with success.

Again, the key is to keep track of when each "layer" of code is being
executed: ASP.NET at the server; javscript at the client.


Todd Gill
Ossia Systems
www.ossia-systems.com

 

[Priya]

You should keep in mind at what point the server code is executed by
the server (asp.net), and at what point the javascript code is
executed by the user's browser (javscript).

There are many ways to get your retrieved database values to your
javascript code. If you can include the javascript code on the
ASP.NET page you're using, it can work like this:

1. Update the javascript code when ASP.NET renders the page

<script language="javascript">

function myFunctionToRunAfterDB()
{
//Use ASP.NET to place your value into javascript code
var dbResultString = <%= strDBResult %>;
}

</script>

In this case, of course strDBResult is a public string for this
ASP.NET page.

2. Pass parameters to the javascript function defined in the
static .js file

If the javascript function you are using is in a static file (such as
myScript.js), a similar method may work as long as the javascript
function accepts parameters for the functions you wish to call (or the
javascript function otherwise has scope):

from myScript.js:
...
function myFunction(strToPrint)
{
alert(strToPrint);
}

from your asp.net page:

...
<script src="myScript.js" language="javascript"></script>
...
<script language="javascript">
//call the function, but pass in the newly-retrieved value
from ASP.NET
// this can also be called from any Javscript event such as
a button's "onClick" event
myFunction(<%= strDBResult %>);
</script>

3. Convert the .js file to an ASP.NET page

In some cases, it may be appropriate to convert your .js file into
a .aspx file. The file would still contain javascript code, but data
from ASP.NET can be added using the same technique I described in item
#1.

I've used all three methods with success.

Again, the key is to keep track of when each "layer" of code is being
executed: ASP.NET at the server; javscript at the client.

Todd Gill
Ossia Systemswww.ossia-systems.com

Guys, Thanks for the help extended. It was very useful.