update session variable on textbox_change without postback - asp.net

Question

is there any way to save textbox text to a session variable without having to postback on text change?

Answer 1

You will need to do this in 4 stages.
1) Add an onkeydown="textChanged(this.ID);" to your textbox
2) Use some Javascript to capture the text
3) Fire an Ajax call to a web method
4) use the web method to store the session variable.
So something like this:
On your textbox, set Autopostback=false so you don't post back on typing.
Create yourself a small Javascript function that will be fired when the user types.
this function will first clear any timer attached to the textbox. then it will create another one that will fire another function after 1 second. This will ensure you're not trying to fire the end function too often.
function textChanged(id) {
var txtBox = document.getElementById(id);
clearTimeout(txtBox.timer);
txtBox.timer = setTimeout('SaveVariable()', 1000);
};
After 1 second, your method will call something like this:
function SaveVariable(){
// Do an ajax call in here and send your textbox value to a web method
var t = // GetYourTextboxTextHere
if (t != "") {
$.ajax({
type: "POST",
url: "yourPage.aspx/SaveMyTextVar",
data: "{'textToSave ': '" + escape(t) + "'}",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (msg) {
if (!msg.d) {
// it didn't save
} else {
// it saved just fine and dandy
};
}
});
};
}
Finally, a small web method on your code behind to capture the text
<ScriptMethod(ResponseFormat:=ResponseFormat.Json)> <Services.WebMethod()> _
Public Shared Function SaveMyTextVar(ByVal textToSave As String) As Boolean
'' Save your variable to session here.
'' return true or false
'' you can capture the returning result in the AJAX that calls this method
End Function