Client-side JavaScript changes the items of the asp.net Dropdownlist control, how to get the selected value in the backg

prince_l

Similar to the city list, there is no item when initializing. According to customer selection, javascript fills the list. After the form is submitted, how does the .cs background code obtain the value of DropDownList?

shenmue024

Request.Form ["name"]
But it takes some effort to save the options

capalex

After the client assigns the value of the dropdownlist, the background code can directly read it with selectedvalue.

zhengminglin

Use client controls.

everever30

Request.Form ["dropdownlistId"]

pyonus

Oh, due to the characteristics of the Dropdownlist control, if it is a value assigned by the front-end JS, the background code cannot directly read the value of the Dropdownlist, and the landlord will find that the value of the Dropdownlist has returned to the initial spatiotemporal state.
The solution is:
Add a TextBox file box and make it invisible. Then select Dropdownlist, use js to assign the value to the TextBox, and read the value in the TextBox in the background when submitting.

solowebwolf

The foreground is saved with <input type = "hidden" id = "txta" name = "txta" runat = "server" />.
Txta.Value is used in the background.

pyonus

Correction: TextBox cannot be set to not hidden, so the background cannot read the value of the TextBox, ^ _ ^ but the foreground color of the TextBox can be set to the same color as the page background to achieve the "invisible" effect.

// Add a foreground event to the background Page_Load:
DropDownList1.Attributes.Add ("onchange", "ToTextBox ()");


// Decisions at the front desk:
function ToTextBox () {
        document.getElementById ("TextBox1"). value = document.all ("DropDownList1"). value;
    }

pyonus

Oh, in the waysolowebwolfbrother said, defining a hidden input is also an option!

prince_l

Too much effort, decided to use the server side