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Multiple javascript methods not called in an expression

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

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);
}

but the second function always returns undefined(the debugger will not "enter" calls eval), while the first function behaves correctly. Is there something that several method calls evalare called in the wrong expression?

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1 answer

You are a victim of semicolon insertion rules .

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);
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