Passing arguments to JavaScript function from code-behind
Question
I would like to call a javascript function from an aspx control. For instance, suppose I had:
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Untitled Page</title>
<script type="text/javascript">
function test(x, y)
{
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Button ID="Button1" runat="server" Text="Button"
onclick="Button1_Click"/>
</div>
</form>
</body>
</html>
and in the code behind:
protected void Button1_Click(object sender, EventArgs e)
{
// do stuff (really going to a database to fill x and y)
int[] x = new int[] { 1, 2, 3, 4, 5 };
int[] y = new int[] { 1, 2, 3, 4, 5 };
// call javascript function as test(x,y);
}
Is there a way to do it?
9 answers
solution1
10 2009-04-25 06:22:55
Look at the ScriptManager.RegisterStartupScript method if you're using a ScriptManager or any Ajax controls/asynchronous postbacks.
Edit:
Actually, the function you want is probably ScriptManager.RegisterClientScriptBlock
solution2
10 ACCPTED 2009-04-25 06:23:09
solution3
6 2009-04-26 05:08:35
Some other things I found out:
You can't directly pass in an array like:
this.Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "xx",
"<script>test("+x+","+y+");</script>");
because that calls the ToString() methods of x and y, which returns "System.Int32[]", and obviously Javascript can't use that. I had to pass in the arrays as strings, like "[1,2,3,4,5]", so I wrote a helper method to do the conversion.
Also, there is a difference between this.Page.ClientScript.RegisterStartupScript() and this.Page.ClientScript.RegisterClientScriptBlock() - the former places the script at the bottom of the page, which I need in order to be able to access the controls (like with document.getElementByID). RegisterClientScriptBlock() is executed before the tags are rendered, so I actually get a Javascript error if I use that method.
http://www.wrox.com/WileyCDA/Section/Manipulating-ASP-NET-Pages-and-Server-Controls-with-JavaScript.id-310803.html covers the difference between the two pretty well.
Here's the complete example I came up with:
// code behind
protected void Button1_Click(object sender, EventArgs e)
{
int[] x = new int[] { 1, 2, 3, 4, 5 };
int[] y = new int[] { 1, 2, 3, 4, 5 };
string xStr = getArrayString(x); // converts {1,2,3,4,5} to [1,2,3,4,5]
string yStr = getArrayString(y);
string script = String.Format("test({0},{1})", xStr, yStr);
this.Page.ClientScript.RegisterStartupScript(this.GetType(),
"testFunction", script, true);
//this.Page.ClientScript.RegisterClientScriptBlock(this.GetType(),
//"testFunction", script, true); // different result
}
private string getArrayString(int[] array)
{
StringBuilder sb = new StringBuilder();
for (int i = 0; i < array.Length; i++)
{
sb.Append(array[i] + ",");
}
string arrayStr = string.Format("[{0}]", sb.ToString().TrimEnd(','));
return arrayStr;
}
//aspx page
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Untitled Page</title>
<script type="text/javascript">
function test(x, y)
{
var text1 = document.getElementById("text1")
for(var i = 0; i<x.length; i++)
{
text1.innerText += x[i]; // prints 12345
}
text1.innerText += "\ny: " + y; // prints y: 1,2,3,4,5
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Button ID="Button1" runat="server" Text="Button"
onclick="Button1_Click" />
</div>
<div id ="text1">
</div>
</form>
</body>
</html>
solution4
3 2011-04-29 08:11:06
include script manager
code behind function
ScriptManager.RegisterStartupScript(this, this.GetType(), "HideConfirmBox", "javascript:HideAAConfirmBox(); ", true);
solution5
2 2009-04-25 06:38:45
Response.Write("<scrip" + "t>test(" + x + "," + y + ");</script>");
分解脚本关键字，因为VStudio / asp.net编译器不喜欢它
solution6
1 2011-01-09 05:23:01
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Call java script function on Code behind</title>
<script type="text/javascript">
function abc()
{
var a=20;
var b=30;
alert("you enter"+a+":"+b);
}
</script>
</head>
cs code
protected void Page_Load(object sender, EventArgs e)
{
TextBox2.Attributes.Add("onkeypress", "return abc();");
}
try this
solution7
0 2013-03-24 16:07:52
<head>
<script type="text/javascript">
function test(x, y)
{
var cc = "";
for (var i = 0; i < x.length; i++)
{
cc += x[i];
}
cc += "\ny: " + y;
return cc;
}
</script>
</head>
<body>
<form id="form1" runat="server">
<asp:Button ID="Button1" runat="server" Text="Button" />
<p>
<asp:TextBox ID="TextBox1" Name="TextBox1" runat="server" AutoPostBack="True" TextMode="MultiLine"></asp:TextBox>
</p>
</form>
</body>
protected void Page_Load(object sender, EventArgs e)
{
int[] x = new int[] { 1, 2, 3, 4, 5 };
int[] y = new int[] { 1, 2, 3, 4, 5 };
string xStr = getArrayString(x); // converts {1,2,3,4,5} to [1,2,3,4,5]
string yStr = getArrayString(y);
string script = String.Format(" var y = test({0},{1}) ; ", xStr, yStr);
script += String.Format(" document.getElementById(\"TextBox1\").value = y ");
this.Page.ClientScript.RegisterStartupScript(this.GetType(), "testFunction", script, true);
// this.Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "testFunction", script, true); // different result
}
private string getArrayString(int[] array)
{
StringBuilder sb = new StringBuilder();
for (int i = 0; i < array.Length; i++)
{
sb.Append(array[i] + ",");
}
string arrayStr = string.Format("[{0}]", sb.ToString().TrimEnd(','));
return arrayStr;
}
solution8
0 2010-06-10 10:10:55
If you are interested in processing Javascript on the server , there is a new open source library called Jint that allows you to execute server side Javascript. Basically it is a Javascript interpreter written in C#. I have been testing it and so far it looks quite promising.
Here's the description from the site:
Differences with other script engines:
Jint is different as it doesn't use CodeDomProvider technique which is using compilation under the hood and thus leads to memory leaks as the compiled assemblies can't be unloaded. Moreover, using this technique prevents using dynamically types variables the way JavaScript does, allowing more flexibility in your scripts. On the opposite, Jint embeds it's own parsing logic, and really interprets the scripts. Jint uses the famous ANTLR ( http://www.antlr.org ) library for this purpose. As it uses Javascript as its language you don't have to learn a new language, it has proven to be very powerful for scripting purposes, and you can use several text editors for syntax checking.
solution9
0 2009-04-25 06:35:51
I think you want to execute the javascript serverside and not in the browser after post-back, right?
That's not possible as far as I know
If you just want to get it execute after postback, you can do something like this:
this.Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "xx", "<script>test("+x+","+y+");</script>");
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