innerHTML in IE

document.getElementById('select').innerHTML = "<option>optie 1</option>";

document.getElementById('select').innerHTML = "<option>optie 1</option>";

function addOption(select, value, content) {
    var elem = document.createElement('option');
    elem.value = value;
    if (content !== undefined) {
        elem.appendChild(document.createTextNode(content));
    }

    select.appendChild(elem);
}

addOption(document.getElementById('select'), 'optie 1');
addOption(document.getElementById('select'), 'optie 2', 'andere waarde!);

function addOption(select, value, content) {
    var elem = document.createElement('option');
    elem.value = value;
    if (content !== undefined) {
        elem.appendChild(document.createTextNode(content));
    }
 
    select.appendChild(elem);
}
 
addOption(document.getElementById('select'), 'optie 1');
addOption(document.getElementById('select'), 'optie 2', 'andere waarde!);