Need help with a function

I want to make a function that will handle focus for multiple forms. I'm certainly doing something wrong here because it isn't working as expected. Can someone tell me what's wrong?

<a href开发者_StackOverflow中文版="#" onclick="x('a','b','')">test</a>

<script type="text/javascript">
function x(xform, xbox, xval) {
  document.xform.xbox.focus();
}
</script>
<input type="text" id="b" name="b" />

Not sure why you need the third value (focus does not take any parameter), but it should look like this:

document[xform][xbox].focus();

DEMO

Explanation: document.xform will access the xform property of document. But document[xform] will access the property taken from the value of xform.

You can use bracket notation as Felix has...however IDs should be unique in a page, so just this would work:

function x(id) {
  document.getElementById(id).focus();
}

Then in your code use the id that your <input> already has:

<a href="#" onclick="x('b')">test</a>