Question

Before I explain my situation, please have a look at the very important notice!!

1.My javascript is not embedded in .aspx file, so something like

    var strMessage = '<%= str%>';
    StartGeocoding(strMessage);

is not working (I tried a lot, but if you can improve it please let me know)

2.Also, I already used

    Page.ClientScript.RegisterStartupScript( , , , )

function, so I think I am not allowed to use twice.

================================================================

So, here
In “Location.js” (seperated from .aspx)

    function LoadMap(count) {       
        var asdf = (something variable from code-behind);
        var counts = count;                      
        myMap = new VEMap("mapDiv");
        myMap.LoadMap();
        StartGeocoding(asdf);    // it will show the map with location info of "asdf"
    }

In code behind, there is something

    public string blahblah = "1 Yonge Street"

Basically, I will get the address from code behind, and I will show it using javascript.
If you (my LORD!) can teach me how to get the variable in C# from javascript, that would be very appreciated!!!

If you guys wanna challenge, here is bonus(?) question

actually, I will show the multiple location in a map. Therefore, instead of having one string “blahblah”, I might have a list of string

    <list>Locationlist        //not array

So, ‘count’ in LoadMap() function will recognize how many entries I have. How to get each location information from javascript? is this possible? Any idea?

Answer 1

Here’s what I had in mind.
On code-behind, let’s say the Page_Load method, you can have the following code:

List<string> locations = new List<string> { "1 Yonge Street", "100 Yonge Street", "123 Microsoft Way" };

//transform the list of locations into a javascript array. 
//The generated script should look like window.myLocations = ['1 Yonge Street', '100 Yonge Street', etc];
StringBuilder script = new StringBuilder();
script.Append("window.myLocations = [");
foreach(string location in locations){
  if(script.Length > 0){
    script.Append(", ");
  }
  script.Append("'"+System.Web.HttpUtility.JavaScriptStringEncode(location) +"'");
}
script.Append("];");

//then register this script via RegisterStartupScript.
Page.ClientScript.RegisterStartupScript( this, this.GetType(), "registerMyLocations", script.ToString(), true);

At this point you can acccess the registered array in Location.js:

function LoadMap(/*count*/) {       
        var asdf = window.myLocations[0]; //this would be '1 Yonge Street' in your case
        alert(asdf);
        //var counts = count;
        var counts = window.myLocations.length;                      
        alert(counts);

        myMap = new VEMap("mapDiv");
        myMap.LoadMap();
        StartGeocoding(asdf);    // it will show the map with location info of "asdf"
    }

Some remarks:

• To use the StringBuilder class you need to add a “using System.Text” at the top of the file;

• the System.Web.HttpUtility.JavaScriptStringEncode is needed to ensure that the serverside strings are correctly encoded (taken from Caveats Encoding a C# string to a Javascript string). It is available only in .Net 4, from what I understand.

• if you have a ScriptManager on the page it is best to use the RegisterStartupScript on the ScriptManager rather then the method in the Page.ClientScript

I cannot test the above code right now but you should get the basic ideea.