Alternative for innerHTML?

The better way of doing it is to use document.createTextNode. One of the main reasons for using this function instead of innerHTML is that all HTML character escaping will be taken care of for you whereas you would have to escape your string yourself if you were simply setting innerHTML.

The recommended way is through DOM manipulation, but it can be quite verbose. For example:

// <p>Hello, <b>World</b>!</p>
var para = document.createElement('p');
para.appendChild(document.createTextNode('Hello, '));

// <b>
var b = document.createElement('b');
b.appendChild(document.createTextNode('World');
para.appendChild(b);

para.appendChild(document.createTextNode('!'));

// Do something with the para element, add it to the document, etc.

EDIT

In response to your edit, in order to replace the current content, you simply remove the existing content, then use the code above to fill in new content. For example:

var someDiv = document.getElementById('someID');
var children = someDiv.childNodes;
for(var i = 0; i < children.length; i++)
    someDiv.removeChild(children[i]);

But as someone else said, I'd recommend using something like jQuery instead, as not all browsers fully support DOM, and those that do have quirks which are dealt with internally by JavaScript libraries. For example, jQuery looks something like this:

$('#someID').html("<p>Hello, <b>World</b>!</p>");