esformatter-collapse-objects

esformatter plugin for conditionally collapsing object and array literals.

Usage

install it:

npm install esformatter-collapse-objects

and something like this to your esformatter config file:

{
  "plugins": [
    "esformatter-collapse-objects"
  ],
  "collapseObjects": {
    "ObjectExpression": {
      "maxLineLength": 80,
      "maxKeys": 3,
      "maxDepth": 1,
      "forbidden": [
        "FunctionExpression"
      ]
    },
    "ArrayExpression": {
      "maxLineLength": 80,
      "maxKeys": 5,
      "maxDepth": 2,
      "forbidden": [
        "FunctionExpression"
      ]
    }
  }
}

Important

In order to collapse Array literals, you need to have esformatter expand them in the first place. Add the following to your esformatter config when collapsing Arrays:

"lineBreak": {
  "before": {
    "ArrayExpressionClosing": 1
  },
  "after": {
    "ArrayExpressionOpening": 1,
    "ArrayExpressionComma": 1
  }
},

Options

Options map esprima AST Node types (in this case both ObjectExpression and ArrayExpression) to their respective options, just like indentation in esformatter.

You can also avoid collapsing literals under certain conditions like a maximum number of keys, or when they contain other nodes like FunctionExpression.

[function foo() { return 'bar' }]

for example, could never occur since FunctionExpression is forbidden when trying to collapse a literal if this is set.

You can also limit the depth of nested literals. All literals begin at a depth of 1, and for performance reasons setting a maxDepth of greater than 3 is ignored. For example, {foo: { bar: 'baz' }} has a depth of two and would be collapsed if the maxDepth is 2 or greater.

The following is the default configuration for the plugin:

{
  ObjectExpression: {
    maxLineLength: 80,
    maxKeys: 3,
    maxDepth: 2,
    forbidden: [
      'FunctionExpression'
    ]
  },
  ArrayExpression: {
    maxLineLength: 80,
    maxKeys: 3,
    maxDepth: 2,
    forbidden: [
      'FunctionExpression'
    ]
  }
}

JavaScript API

Register the plugin and call esformatter like so:

// register plugin
esformatter.register(require('esformatter-collapse-objects'));
// pass options as second argument
var output = esformatter.format(str, {
  "collapseObjects": {
    "ObjectExpression": {
      maxLineLength: 80,
      maxKeys: 3,
      maxDepth: 1,
      forbidden: [
        'FunctionExpression'
      ]
    },
    "ArrayExpression": {
      maxLineLength: 80,
      maxKeys: 5,
      maxDepth: 2,
      forbidden: [
        'FunctionExpression'
      ]
    }
  }
});

License

Released under the MIT License.

Credits

Huge thanks to Jörn Zaefferer, who published an MIT-licensed gist which serves as the foundation for this module.