A Prettier JavaScript Formatter

Post by kajecounterhack » Tue, Jan 10, 2017, 7:35 PM UTC

overcast wrote: post #59

Dangeranger wrote: post #58

After using Elm and the elm-format package in Emacs for the last few weeks I can say that not having to format the source and just letting your editor do it for you on save or via a command is so very nice. This is a trend that I feel is going to catch on across any language that can support it. It makes trivial decisions and arguments about formatting a thing of the past.

It's almost crazy to think this already isn't just a thing. Why is this just coming to a head now, after all these years of carrying on over code formatting?

Post by [deleted] » Tue, Jan 10, 2017, 7:40 PM UTC

k__ wrote: post #51

imh wrote: post #42

Earlier quoted context omitted.

I don't do much serious JS. What's the problem there?

JavaScript has automatic semicolon insertion (ASI). This will add semicolons all over your code depending on some rules, for example, if you write a return, and write the value you want to return in the next line, it adds a semicolon after the return AND after the value, effectively ignoring the value in the end. return myValue; becomes return; myValue; It's a bit meh, because you have to remember these rules even if…

Post by gopher_protocol » Tue, Jan 10, 2017, 7:44 PM UTC

tomp wrote: post #14

Nice attempt, but currently wrong. For example, it pretty-formats this code: function makeComponent() { return /*test*/ { a: 1 }; } into function makeComponent() { return /*test*/ { a: 1 }; } From my own experience writing a formatter, comments are very difficult (if one wants to preserve them). I guess the author should reparse the generated code to ensure the AST hasn't changed.

    function doSomething() : int {
      return myPromise
      .then(() => {
        // ...do thing
        /* what */
      })
      .catch(() => {
        // ..do other thing
        /* the heck */
      });
    }

    function doSomething(): int {
      return myPromise
        .then(() => {})
        .catch(() => {});
    }

Post by zem » Tue, Jan 10, 2017, 7:46 PM UTC

Dangeranger wrote: post #58

After using Elm and the elm-format package in Emacs for the last few weeks I can say that not having to format the source and just letting your editor do it for you on save or via a command is so very nice. This is a trend that I feel is going to catch on across any language that can support it. It makes trivial decisions and arguments about formatting a thing of the past.

Post by estebank » Tue, Jan 10, 2017, 7:52 PM UTC

nailer wrote: post #55

This is awesome, but one request: can you please extend it into a real (ie, AST based) diffing tool? Current diffing tools all compare the text (which is basically an input format) rather than the AST, and hence end up focusing on formatting rather than actual changes.

    --val  x =  [1]
    ++var x = [
    ++  1,
    ++];

    --val x = [short(), short()];
    ++val x = [
    ++  a_really_long_name_that_pushes_the_line_length(),
    ++  a_really_long_name_that_pushes_the_line_length(),
    ++];