JavaScript で選択した要素にオプションをプログラム的に入力するにはどうすればよいですか?

<code class="javascript">var min = 12;
var max = 100;
var select = document.getElementById('mainSelect');

for (var i = min; i <= max; i++){
    var opt = document.createElement('option');
    opt.value = i;
    opt.innerHTML = i;
    select.appendChild(opt);
}</code>

<code class="javascript">function populateSelect(target, min, max){
    if (!target){
        return false;
    }
    else {
        var min = min || 0;
        var max = max || min + 100;

        var select = document.getElementById(target);

        for (var i = min; i <= max; i++){
            var opt = document.createElement('option');
            opt.value = i;
            opt.innerHTML = i;
            select.appendChild(opt);
        }
    }
}</code>

<code class="javascript">HTMLSelectElement.prototype.populate = function (opts) {
    var settings = {};

    settings.min = 0;
    settings.max = settings.min + 100;

    for (var userOpt in opts) {
        if (opts.hasOwnProperty(userOpt)) {
            settings[userOpt] = opts[userOpt];
        }
    }

    for (var i = settings.min; i <= settings.max; i++) {
        this.appendChild(new Option(i, i));
    }
};</code>