rollup-merge-config: extend configurations with ease.

Rollup-merge-config provides merge and extend function that helps in merging/extending roll-up configs with ease. It provides array concatenation and object merging functionality.

It also supports custom array as well as custom object merge.

Basic Merge Capability

merge(...configuration | [...configuration])

merge is the core of the API. This is all you need unless you want further customization.

// Default API
const output = merge(object1, object2, object3, ...);
//or
const output = merge([object1, object2, object3]);

//Example:
const output = merge(
  { type: "i20", brand: "hyundai" },
  { type: "verna" }
);
// output:
// { type: "i20", brand: "hyundai", segment: "hatchback"}

// In case the keys match across different objects.
// the latter will take precedence.
const output = merge(
  { type: "i20", brand: "hyundai" },
  { type: "verna" }
);
// output:
// { type: "verna", brand: "hyundai" }

merge({ arrayCustomizer, objectCustomizer })(...configuration | [...configuration])

merge behavior can be customized through a customization API.

// Customizing array/object behavior
const output = merge(
  {
    arrayCustomizer(a, b, key) {
      if (key === 'bar') {
        return _.uniq([...a, ...b]);
      }

      // Fall back to default merging
      return undefined;
    },
    objectCustomizer(a, b, key) {
      if (key === 'foo') {
        // Custom merging
        return _.merge({}, a, b);
      }

      // Fall back to default merging
      return undefined;
    }
  }
)(object1, object2, object3, ...);

// Example
//config1
{
    foo: ['obj1', 'obj2'],
    bar: {name: 'obj1'}
}

//config2
{
    foo: ['obj2', 'obj3'],
    bar: {name2: 'obj2'}
}

//merged output
{
  foo: ['obj1', 'obj2', 'obj3'],
  bar: {name: 'obj1', name2: 'obj2'}
}

In the above example, arrayCustomizer will be invoked for each property of Array type, i.e:

arrayCustomizer(['obj1', 'obj2'], ['obj2', 'obj3'], 'foo');

and objectCustomizer will be invoked for each property of Object type, i.e:

objectCustomizer({name: 'obj1'}, {name2: 'obj2'}, 'bar');