You shouldn't be using onClick any more if you are using jQuery. jQuery provides its own methods of attaching and binding events. See .click()
$(document).ready(function(){
var js = "alert('B:' + this.id); return false;";
// create a function from the "js" string
var newclick = new Function(js);
// clears onclick then sets click using jQuery
$("#anchor").attr('onclick', '').click(newclick);
});
That should cancel the onClick function - and keep your "javascript from a string" as well.
The best thing to do would be to remove the onclick="" from the <a> element in the HTML code and switch to using the Unobtrusive method of binding an event to click.
You also said:
Using
onclick = function() { return eval(js); }doesn't work because you are not allowed to use return in code passed to eval().
No - it won't, but onclick = eval("(function(){"+js+"})"); will wrap the 'js' variable in a function enclosure. onclick = new Function(js); works as well and is a little cleaner to read. (note the capital F) -- see documentation on Function() constructors