What convinced you? I read it and saw something wildly different, which is best reserved for a good reason. The reason appears to be visual recognition of delimiter mistakes that the parser will catch anyway.

The gist contains examples of various mistakes in both styles. Most of the errors are syntax error which will be immediately rejected by a parser. While the comma first errors are generally more obvious, they are silently bad by unexpectedly returning undefined. The standard "var" example is silently bad by leaking vars into the global scope when chaining initializers on a single "var". My conclusion from these samples is that comma prefix formatting only practically helps to prevent hidden mistakes in chained "var"s. Putting each variable declaration on a line of its own is far less distracting than reformatting every list and object.

Sample comma first style error. This seems like a strange thing to do, but I'm unfamiliar with this style.

    return
      { a : "ape"
      , b : "bat"
      } // returns undefined,
        // then creates a block with two named statements.

    var a = "ape eat banana",
      b = "bat, allowed to fly",
      c = "cat toy",
      d = "dog chasing the mailman,"
      e = "elf lord",
    ....
    // leaks "e" into global scope