How to Flatten Nested Objects Concisely in JavaScript?

Flattening Nested Objects Concisely

Transforming a nested object into a flattened structure is often required in various programming scenarios. For a quick and efficient solution, you can utilize a concise one-liner.

To flatten the provided nested object:

{
  a:2,
  b: {
    c:3
  }
}

into the desired output:

{
  a:2,
  c:3
}

Employ the following JavaScript expression:

Object.assign({}, ...function _flatten(o) { return [].concat(...Object.keys(o).map(k => typeof o[k] === 'object' ? _flatten(o[k]) : ({[k]: o[k]})))}(yourObject))

The core concept behind this approach is to recursively create an array of one-property objects. The Object.keys(o) method retrieves all the keys of the input object o. Each key k is then checked for object type. If typeof o[k] === 'object', the function _flatten is recursively applied to the nested object. Otherwise, it constructs a one-property object with the key k and value o[k].

The [].concat(... syntax combines all these one-property objects into a single array. Finally, Object.assign({}, ...) merges these arrays into the desired flattened output.

For readability, the code can be reformatted into the following:

Object.assign(
  {},
  ...function _flatten(o) {
    return [].concat(...Object.keys(o)
      .map(k =>
        typeof o[k] === 'object' ?
          _flatten(o[k]) :
          ({[k]: o[k]})
      )
    );
  }(yourObject)
)

This one-liner effectively flattens nested objects, providing a concise and efficient solution for your data transformation needs.

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