JavaScript <input> history with arrow buttons, a.k.a. poor man's readline

inputhistory.js

/**
 * License: WTFPL - http://www.wtfpl.net/
 * 
 * Usage: element.addEventListener('keydown', inputHistory());
 */
function inputHistory(max_history) {
    var PREV = 38, NEXT = 40, ENTER = 13,
        history = [''], current = 0;

    if (!max_history) {
        max_history = 100;
    }

    return function (event) {
        switch (event.which) {
            case ENTER:
            if (this.value.trim().length) {
                history[current] = this.value;
                history.unshift('');
                current = 0;
                if (history.length > max_history) {
                    history = history.slice(0, max_history);
                }
            }
            break;

            case PREV:
            if (current + 1 < history.length) {
                event.preventDefault();
                history[current] = this.value;
                current += 1;
                this.value = history[current];
            }
            break;

            case NEXT:
            if (current - 1 >= 0) {
                event.preventDefault();
                history[current] = this.value;
                current -= 1;
                this.value = history[current];
            }
            break;
        }
    };
}