JS: How to make document.getElementById cross-browser?

Question

document.getElementById doesn\'t seem to work across all browsers (I mean some old ones) and I am sure there are developers who are not aware of this.

Answer 1

function getDOM() {
    if (document.getElementById) {
        return document.getElementById; 
    }

    var window_document = window.document || {};
    var elements = window_document.all || window_document.layers;
    if(elements) {
        return function(x) { return elements[x]; }
    }

    // everything failed
    throw new InternalError('No means to "getElementById"');
}

... then

var getElementById;
try {
    getElementById = getDOM();
} catch(err) {
    alert(err);
}
// implicit 0K
var oHTMLElement = getElementById('#main');