var textNodes = [];
var textNodes_data = [];
var i=0;
 
function search_textNodes(b) {
    b = b.childNodes;
    for (var c = 0, d = b.length; c < d; c++) {
        var a = b[c];
        if (a.nodeType == 3) {
            textNodes.push(a);
            textNodes_data.push(a.data);
            a.data = ""
        } else a.hasChildNodes() && search_textNodes(a)
    }
};
 
var d = document.getElementById('test');
search_textNodes(d);
function str_write() {
    var a = textNodes_data[i];
    if (a) {
        textNodes[i].data += a.charAt(0);
        textNodes_data[i] = a.substr(1)
    } else i++;
    i < textNodes.length && setTimeout(arguments.callee, 90)
 
};
 
str_write()