multiple javascript methods calls not invoked in expression

javascript

Solution

You're a victim of the rules of semicolon insertion.

Try:

return tileCorners[a].eval(u,v) +
tileCorners[b].eval(u-1,v) +
tileCorners[c].eval(u,v-1) +
tileCorners[d].eval(u-1,v-1);

Your version is equivalent to:

return;

tileCorners[a].eval(u,v) +
tileCorners[b].eval(u-1,v) +
tileCorners[c].eval(u,v-1) +
tileCorners[d].eval(u-1,v-1);

Problem

The JavaScript function ``` function tile(u,v, a,b,c,d) { var c0 = tileCorners[a].eval(u,v); var c1 = tileCorners[b].eval(u-1,v); var c2 = tileCorners[c].eval(u,v-1); var c3 = tileCorners[d].eval(u-1,v-1); return c0 + c1 + c2 + c3; } ``` should be equivalent to ``` function tile(u,v, a,b,c,d) { return tileCorners[a].eval(u,v) + tileCorners[b].eval(u-1,v) + tileCorners[c].eval(u,v-1) + tileCorners[d].eval(u-1,v-1); } ``` yet the second function always returns `undefined` (the debugger will not "step into" the calls to `eval`) whereas the first function behaves correctly. Is there something about having multiple `eval` method calls in an expression that is wrong?

Original source