using a href to call javascript function with parameter

I'm trying to call javascript function from a href . the function has a parameter which will be retrieved by the eval function . But some error occurs .

script:

function rate(id) {

            // do something
        }

the a tag that will call 开发者_开发问答the function:

<a href="javascript:rate(" + <%#Eval("ID")%> + ")" >rate</a>

What am I missing ?

You shouldn't be doing it like this, but the issue you're currently up against is probably is your quoting/concatenating.

If <%#Eval("ID")%> simply produces an INT, this should work:

<a href="javascript:rate( <%#Eval("ID")%> )" >rate</a>

If it's a string,

<a href="javascript:rate( '<%#Eval("ID")%>' )" >rate</a>

should do it for you, although you need to handle the case of <%#Eval("ID")%> producing anything with a single quote in it.

A Lesson:

I say you shouldn't be doing it like this because the javascript pseudo protocol (javascript:) is defunct and improper. At worst you should be using an onclick which returns false. Ideally you'd be assigning the event programatically and preventing the event object's default action.

I don't see any need for the use of eval() at all. Code in quotes like this is evaluated at the top level scope. If you make sure that both rate and ID are defined at that top level scope, then it will work without eval() with this HTML:

<a href="#" onclick="rate(ID);">rate</a>

and this code:

var ID = 3;

function rate(id) {
    alert(id);
    return(false);
}

You can see it work here: http://jsfiddle.net/jfriend00/bqqpM/. The trick to making this work without eval is just making sure that ID and rate are both available at the top level scope.

You shouldn't use " + + ", because it will just be replaced with a number:

<a href="javascript:rate(<%#Eval("ID")%>)">rate</a>

Why call it as an href? You can just make a button and style it like a link. That would be a lot easier

<button id = "myButton" onclick = "rate(<%#Eval("ID")%>)" >rate</button>

#myButton
{
  border: none;
  padding: none;
  background-color: transparent;
}