How to unflatten an object with the paths for keys in JavaScript?

In JavaScript, an object can be "flattened" by creating a shallow copy of it. This is useful for creating a snapshot of an object, but can cause problems if the object is later modified. If you need to unflatten an object, you can use the paths for keys to restore the original structure.

Using Paths for Keys

When an object is flattened, the keys are concatenated into a single string. You can use this string to unflatten the object by creating an object with the same keys and values.

For example, consider the following object.

var obj = { "": "baz", "foo.qux": "quux" };

You can unflatten this object by creating an object with the same keys and values.

<!doctype html> <html> <head> <title>Examples</title> </head> <body> <div id="result1">Original Object:</div><br/> <div id="result2">After Unflatten:</div> <script> var obj = { "": "baz", "foo.qux": "quux" }; var unflattenedObj = {}; for (var key in obj) { var value = obj[key]; var path = key.split("."); var current = unflattenedObj; for (var i = 0; i < path.length - 1; i++) { var part = path[i]; current[part] = current[part] || {}; current = current[part]; } current[path[path.length - 1]] = value; } document.getElementById("result1").innerHTML += JSON.stringify(obj); document.getElementById("result2").innerHTML += JSON.stringify(unflattenedObj); console.log(unflattenedObj) </script> </body> </html>

Benefits of Unflattening

Unflattening an object can be useful for a number of reasons. First, it can help you avoid duplicate keys. If you have two keys with the same name, they will be overwritten when the object is flattened. Second, it can help you preserve the original structure of the object. This can be important when you need to pass the object to a function that expects a certain format.


Unflattening an object is a simple matter of creating an object with the same keys and values. This can be useful for avoiding duplicate keys and preserving the original object structure.