Martin Probst's weblog

clang-format for JavaScript

Thursday, January 15, 2015, 16:24 — 0 comments Edit

clang-format is a very neat code formatter developed as part of the Clang project by my colleague Daniel Jasper here at Google. It’s so good that many projects have decided to just completely rely on clang-format and never indent code manually nor use a linter. clang-format is reasonably well known in the C++ community by now, but it’s much less well known that it also works for a bunch of other vaguely ALGOL-shaped programming languages. I’ve been working a bit with Daniel to make sure it works on JavaScript, which sorely lacks a robust formatter.

Two days ago my pull request to Homebrew was accepted (yay!), so you can now easily install clang-format on any Mac and enjoy awesome code formatting.

  1. Install homebrew
  2. brew install clang-format
  3. There’s no step three

Now when you run clang-format -style=Google somefile.js, it’ll automatically spit a nicely indented version back at you. For example this terrible mess:

function Foo() {
     this.bar =
    function() {this.doX(); this.doY();
  for (var x =
0; x < 12; x++) { if (this.z) 
    new 
 Foo(). callWithArgs   (
        {arg1: 'hello',
arg2: 'world'});}
    };          this.baz = 123;
           this.bam = {some: 'object literal', including: function() { calls(); }, asdSomeMoreKeysToWrap: 123};
}

With one keypress turns into this nicely indented piece:

function Foo() {
  this.bar = function() {
    this.doX();
    this.doY();
    for (var x = 0; x < 12; x++) {
      if (this.z) new Foo().callWithArgs({arg1: 'hello', arg2: 'world'});
    }
  };
  this.baz = 123;
  this.bam = {
    some: 'object literal',
    including: function() { calls(); },
    asdSomeMoreKeysToWrap: 123
  };
}

I really like it - it takes a lot of the tedium out of writing code, and its indentation is really beautiful - usually much nicer than what I would bother with on a typical day.

clang-format already has integration with many editors, e.g. vim, or Sublime Text, and the command line is straight forwad to use.

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