if (axis === 'x') return this.zoomed_x_;
if (axis === 'y') return this.zoomed_y_;
throw "axis parameter is [" + axis + "] must be null, 'x' or 'y'.";
if (axis === 'x') return this.zoomed_x_;
if (axis === 'y') return this.zoomed_y_;
throw "axis parameter is [" + axis + "] must be null, 'x' or 'y'.";