17.07.forceToUpperCase.js

function forceToUpperCase(element) {
    if (typeof element === "string") element = document.getElementById(element);
    element.oninput = upcase;
    element.onpropertychange = upcaseOnPropertyChange;

    // Easy case: the handler for the input event
    function upcase(event) { this.value = this.value.toUpperCase(); }
    // Hard case: the handler for the propertychange event
    function upcaseOnPropertyChange(event) {
        var e = event || window.event;
        // If the value property changed
        if (e.propertyName === "value") {
            // Remove onpropertychange handler to avoid recursion
            this.onpropertychange = null;
            // Change the value to all uppercase
            this.value = this.value.toUpperCase();
            // And restore the original propertychange handler
            this.onpropertychange = upcaseOnPropertyChange;
        }
    }
}