The determinant of the jacobi matrix of $x\mapsto \frac{x}{|x|^2}$

Question

I want to calculate the determinant of the jacobian of the map

$\phi$: $\mathbb R^n\rightarrow \mathbb R^n$, $x\mapsto \frac{x}{|x|^2}$

Since this maps doesnt seems to be linear I dont know how to do it :/

Any help is appreciated