Add one handler in terms of another?

I have a tag with a complex "oninput" handler, e.g.

 <input id="x" type="text" name="x"  
  oninput="lotsofgeneratedcocde...."/>

I want to add another handler that simply calls that one. My initial though was that 开发者_高级运维this would work:

 <input id="x" type="text" name="x"  
  oninput="lotsofgeneratedcocde...." onfocus="this.oninput"/>

But it doesn't. What should I be doing? Thanks.

Edit: I thought that onfocus="this.oninput" would copy the reference to the function, that's why I left off the parentheses for a call.

this.oninput() (note parentheticals) should work:

<input id="x" type="text" name="x"  
       oninput="console.log('test');" onfocus="this.oninput();"/>

http://jsfiddle.net/9kNrW/

This could work?

... onfocus="this.oninput()"

I assume there's no way to have the generated code be outsourced as proper functions that you could call from both event handlers...

Short answer:
Use parens: onfocus="this.oninput();"

If oninput references this or the event object, you need to add a little more:

onfocus="this.oninput.call(this, event);"

Explanation:
If you were attaching the event handlers in code, your syntax is correct. Because you are setting a function reference. Ie,

myInput.onfocus = myInput.oninput;

But, when attached in the markup, the code between the quotes actually is itself a function. Eg,

<span id="foo" onclick="alert('hello world');" />

Is equivalent to:

document.getElementById("foo").onclick = function () {
    alert('hello world');
};

So your code as written is the equivalent of:

document.getElementById("x").onfocus = function () {
    this.oninput; // returns a function reference.  Does not call the function.
};