Square $ABCD$ and equilateral triangle $AED$ are coplanar and share $\overline{AD}$, as shown. What is the measure, in degrees, of angle $BAE$? [asy] size(3cm);
pair A,B,C,D,E;
A = (0,0);
B = (0,1);
C = (1,1);
D = (1,0);
E = dir(60);
draw(A--B--C--D--E--A--D);
label("$A$",A,dir(180));
label("$B$",B,dir(180));
label("$C$",C,dir(0));
label("$D$",D,dir(0));
label("$E$",E,dir(0));
[/asy]
The angles in a triangle sum to 180 degrees, so the measure of each angle of an equilateral triangle is 60 degrees.  Therefore, the measure of angle $EAD$ is 60 degrees.  Also, angle $BAD$ measures 90 degrees.  Therefore, the measure of angle $BAE$ is $90^\circ-60^\circ=\boxed{30}$ degrees.