I'm attempting to call a javascript method in its own file from code behind on a button click.
aspx file
protected void Next_Click(object sender, EventArgs e)
{
if (hidden.Value == "")
{
Response.Write(@"<script language='javascript'>drawImage();</script>");
}
}
js file
function drawImage() {
context.drawImage(video, 0, 0, 320, 240);
var imgBase = canvas.toDataURL('image/jpeg');
document.getElementById("hidden").value = imgBase;
}
The problem is that this wont call the draw image method, i suspect it's cause the js file is its own file but i'm not sure.
Any help you could give would be greatly appreciated.
I'm attempting to call a javascript method in its own file from code behind on a button click.
aspx file
protected void Next_Click(object sender, EventArgs e)
{
if (hidden.Value == "")
{
Response.Write(@"<script language='javascript'>drawImage();</script>");
}
}
js file
function drawImage() {
context.drawImage(video, 0, 0, 320, 240);
var imgBase = canvas.toDataURL('image/jpeg');
document.getElementById("hidden").value = imgBase;
}
The problem is that this wont call the draw image method, i suspect it's cause the js file is its own file but i'm not sure.
Any help you could give would be greatly appreciated.
Share Improve this question asked May 7, 2013 at 3:57 TurtleTopiaryTurtleTopiary 1332 gold badges2 silver badges7 bronze badges3 Answers
Reset to default 1see http://msdn.microsoft./de-de/library/z9h4dk8y.aspx
try this
string jquery = "drawImage();"
ClientScript.RegisterStartupScript(typeof(Page), "a key",
"<script type=\"text/javascript\">"+ jquery +"</script>"
);
1). If the function is stored in external file (e.g. MyScript.js) then you should include it in the <head> section of the web page and add onclick event to the button, like:
ButtonName.Attributes.Add("onclick", {YourFunction});
in Page_Load event.
2) Another approach is to assign the entire javascript function to a string variable and then pass it instead of {YourFunction} prefixed with javascript:. In this case you don't even need the external file.
Hope it will help. My best, Alex
I presume you already included the script file in your page.
If you require the postback, you need ClientScriptManager.RegisterStartupScript Method (Type, String, String, Boolean) ..
protected void Next_Click(object sender, EventArgs e)
{
if (hidden.Value == "")
{
ClientScriptManager cs = Page.ClientScript;
cs.RegisterStartupScript(this.GetType(), 'startupScript', 'drawImage();', true);
}
}
More Info from SO
You can call the function from your button itself, without the postback.
<asp:Button runat="server" ID='next' OnClientClick="return drawImage();" />
and in the script
function drawImage() {
if(document.getElementById("hidden").value != undefined || document.getElementById("hidden").value != "")
{
context.drawImage(video, 0, 0, 320, 240);
var imgBase = canvas.toDataURL('image/jpeg');
document.getElementById("hidden").value = imgBase;
return false;
}
}