Get the value at given path of an object

Follow a dot-separated path, stopping at a missing step.

JavaScript Version 1.0.0 · MIT · .md

function getValue({ path, object }) { return path.split('.').reduce((value, key) => (value == null ? undefined : value[key]), object) ?? null; }

Input & expected output

{
  "path": "delivery.recipient.status",
  "object": {
    "delivery": {
      "recipient": {
        "status": "delivered"
      }
    }
  }
}

"delivered"

The edge case

{
  "path": "delivery.smtp.code",
  "object": {
    "delivery": {}
  }
}

null

Know the limits

• Missing paths return null here (undefined in the original), so the result is JSON-representable.
• The original stopped at any falsy value, so a 0 or "" on the path hid deeper keys; only null and undefined stop here.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Keep exploring

• Pick properties from an object — Build a new object with only the requested own properties.
• Omit properties from an object — Keep the own enumerable fields that are not in a supplied list.
• Create an object from pairs of key and value — Turn [key, value] pairs into a plain object with Object.fromEntries.