How can I avoid autorepeated keydown events in JavaScript?

Question

If the user holds down the key, multiple keydown events are fired. For usability reasons I need to use keydown, not keyup, but I want to avoid this situation. My relevant co

Answer 1

So, if the existing solution seems dubious (it doesn't consider the case when 2 or more buttons is pressed simultaneously), I suggest another solution that takes it into account.

The _prevKeyDown object is to store keys that are currently pressed.

    _prevKeyDown = {}

    function _downKey( event )
    {
        var wh = event.which;
        var kC = event.keyCode;

        if( _prevKeyDown[ wh ] == null )
        {
            _prevKeyDown[ wh ] = {};
        }

        _prevKeyDown[ wh ][ kC ] = true;
    };

    function _upKey( event )
    {
        var wh = event.which;
        var kC = event.keyCode;

        if( _prevKeyDown[ wh ] != null )
        {
            _prevKeyDown[ wh ][ kC ] = null;
        }               
    };

    function _isKeyDown( event )
    {
        var wh = event.which;
        var kC = event.keyCode;

        var result = false;

        if( this._prevKeyDown[ wh ] != null )
        {
            if( this._prevKeyDown[ wh ][ kC ] == true )
            {
                result = true;
            }
        }

        return result;
    }

    // now your keydown/keyup handlers
    function keydown( event )
    {
        if( !_isKeyDown( event ) )
        {
            // your once-keydown handler here
            _downKey( event );
        }    
    }

    function keyup( event )
    {
        _upKey( event );
    }