Custom throttle extender for knockout.js that throttles input but updates the binding immediately when blurring the text field bound to it. Based on the original throttle extender.

smart_throttle.js

    ko.extenders.smart_throttle = function(target, timeout) {
        target['throttleEvaluation'] = timeout;
        target['lastUpdatedValue'] = null;

        var writeTimeoutInstance = null;
        return ko.computed({
            'read': target,
            'write': function(value) {
                if (value == target()) {
                    clearTimeout(writeTimeoutInstance);
                    target(target['lastUpdatedValue']);
                    return;
                }

                clearTimeout(writeTimeoutInstance);
                target['lastUpdatedValue'] = value;
                writeTimeoutInstance = setTimeout(function() {
                    target(value);
                }, timeout);
            }
        });
    }