121                 function generatePerspectivematrix(x_scale, y_scale, z_near, z_far)
122                 {
123                   return new   Float32Array([z_near/x_scale,      0.0,                           0.0,                                       0.0,
124                                                                 0.0,                z_near/y_scale,                  0.0,                                       0.0,
125                                                                 0.0,                        0.0,         -(z_far+z_near)/(z_far-z_near),            -1.0,
126                                                                 0.0,                        0.0,            -2*z_far*z_near/(z_far-z_near),        0.0]);
127                 }

Notes

At first glance, this code might not match the the full projection matrix from the online references.

Me make significant simplifications using top-bottom and left-right symmetry.

$\mathrm{right}=-\mathrm{left}=\mathrm{xscale}$
        
 and 
        
$\mathrm{top}=-\mathrm{bottom}=\mathrm{yscale}$
        
 Substituting these values into the full matrix gives the much simpler version used in the code. 
$\left[\begin{array}{cccc}\frac{z_{\mathrm{near}}}{\mathrm{xscale}}& 0& 0& 0\\ 0& \frac{z_{\mathrm{near}}}{\mathrm{yscale}}& 0& 0\\ 0& 0& \frac{z_{\mathrm{far}}+z_{\mathrm{near}}}{z_{\mathrm{far}}-z_{\mathrm{near}}}& \frac{-2z_{\mathrm{far}}{z}_{\mathrm{near}}}{z_{\mathrm{far}}-z_{\mathrm{near}}}\\ 0& 0& -1& 0\end{array}\right]$