all_textareas.js

(function() {
    var Dom = YAHOO.util.Dom,
        Event = YAHOO.util.Event;

    Event.onDOMReady(function() {
        var textareas = document.body.getElementsByTagName('textarea'),
            len = textareas.length,
            editors = [];
        for (var i = 0; i < len; i++) {
            editors[i] = new YAHOO.widget.SimpleEditor(textareas[i], {
                height: '300px',
                width: '700px',
            });
            editors[i].render();
        }
    });

})();