Create dot notation array of strings from an Object

By Maxim Polak

Last night, I created an object from an array of strings with dot notation; I needed to do that because I had previously flattened an object into those strings. I did this long and laboriously, but I asked a colleague to see if he could figure out how to do it using recursion. He did, and I'd like to share it here.

If we have this object:

{
  "thingOne": {
    "thingTwo": {
      "thingThree": true,
      "thingFour": true
    }
  },
  "thingyOne": {
    "thingyTwo": {
      "thingyThree": true,
      "thingyFour": true
    }
  }
}

Then this code:

(() => {

  const obj = {
    "thingOne": {
      "thingTwo": {
        "thingThree": true,
        "thingFour": true
      }
    },
    "thingyOne": {
      "thingyTwo": {
        "thingyThree": true,
        "thingyFour": true
      }
    }
  }

  const getObjStringsArr = (o = {}, arr = [], name = '') => {
    Object.keys(o).forEach(key => {
      if (o[key] === true) {
        arr.push(`${name}${key}`)
      } else {
        const nested = getObjStringsArr(o[key], arr, `${name}${key}.`)
        arr.concat(nested)
      }
    });
    return arr
  }

  console.log(getObjStringsArr(obj))

})()

It's brilliant having colleagues; it's even better having colleagues with huge brains! Thanks, Hamish!

It's not necessarily faster than my cludge, but it is far more elegant!