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Javascript has automatic semicolon insertion. This function: function a() { return true; } return undefined.

• JeremyBanks 15y ago
  This Python def a(): return False; returns None.
  • qntm 15y ago
    That's because in Python the line break is the statement terminator.
    • JeremyBanks 15y ago
      Python and JavaScript both accept semicolons or line breaks to terminate statements. JavaScript's syntax problems are a bit more subtle than just that.
  • riffraff 15y ago
    Same in ruby def foo return true end returns "nil"
• knowtheory 15y ago
  I don't like referring to this as "automatic semicolon insertion". The behavior you're referring to here is really about line termination/continuation. var a = 42 is only parseable one way because assignment requires an argument. Javascript just happens to make assumptions with certain kinds of ambiguities, but then, all programming languages do.
  • program 15y ago
    Actually that is the name that appears in the ECMAScript official language specification: http://bclary.com/2004/11/07/#a-7.9.1 http://bclary.com/2004/11/07/#a-7.9.1
    • knowtheory 15y ago
      that just makes me a bit depressed then :) Thanks for the reference. I still think this is a general issue, and calling it semicolon insertion confuses the issue :\
      • olavk 15y ago
        Well, it is the combination of semicolon-insertion and restricted productions.