Lenght between a dot and a line //JavaScript Function (See related posts)

//+ Jonas Raoni Soares Silva
//@ http://jsfromhell.com/math/dot-line-length [v1.0]

dotLineLength = function( x, y, x0, y0, x1, y1, o ){
	function lineLength( x, y, x0, y0 ){
		return Math.sqrt( ( x -= x0 ) * x + ( y -= y0 ) * y );
	}
	if( o && !( o = function( x, y, x0, y0, x1, y1 ){
		if( !( x1 - x0 ) ) return { x: x0, y: y };
		else if( !( y1 - y0 ) ) return { x: x, y: y0 };
		var left, tg = -1 / ( ( y1 - y0 ) / ( x1 - x0 ) );
		return { x: left = ( x1 * ( x * tg - y + y0 ) + x0 * ( x * - tg + y - y1 ) ) / ( tg * ( x1 - x0 ) + y0 - y1 ), y: tg * left - tg * x + y };
	}( x, y, x0, y0, x1, y1 ), o.x >= Math.min( x0, x1 ) && o.x <= Math.max( x0, x1 ) && o.y >= Math.min( y0, y1 ) && o.y <= Math.max( y0, y1 ) ) ){
		var l1 = lineLength( x, y, x0, y0 ), l2 = lineLength( x, y, x1, y1 );
		return l1 > l2 ? l2 : l1;
	}
	else {
		var a = y0 - y1, b = x1 - x0, c = x0 * y1 - y0 * x1;
		return Math.abs( a * x + b * y + c ) / Math.sqrt( a * a + b * b );
	}
};