Flatten assorted array using ramda

Question

I have the following data structure which contains Date objects, some of which are nested inside objects:

[
  new Date("2018-11-20T09:00:00.000Z"),
  new Date("2018-11-19T09:00:00.000Z"),
  {
    "before": new Date("2018-12-14T00:00:00.000Z")
  }
]

Using ramda, I'd like to flatten it so that it becomes:

[
  new Date("2018-11-20T09:00:00.000Z"),
  new Date("2018-11-19T09:00:00.000Z"),
  new Date("2018-12-14T00:00:00.000Z")
]

I've tried using a combination of map , values , unnest and flatten but with no luck. I would ideally like this to work so that it would flatten regardless of the nested object and key names.

Answer 1

Use R.when with R.has and R.prop to extract the value from objects that has the property inside a map.

 const { pipe, map, when, has, prop } = R; const extractOrVal = (p) => map(when(has(p), prop(p))); const extractOrValBefore = extractOrVal('before'); const data = [ new Date("2018-11-20T09:00:00.000Z"), new Date("2018-11-19T09:00:00.000Z"), { "before": new Date("2018-11-14T00:00:00.000Z") } ]; console.log(extractOrValBefore(data)); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script> 

If there can be multiple keys, or you don't know the name of the keys, you can use R.values. This extracts all values from objects, that are not Date:

 const { chain, values, unless, is } = R; const extractAndFlatten = chain(unless(is(Date), values)); const data = [ new Date("2018-11-20T09:00:00.000Z"), new Date("2018-11-19T09:00:00.000Z"), { "before": new Date("2018-12-14T00:00:00.000Z") } ]; console.log(extractAndFlatten(data)); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script> 

And another suggestion by Scott Christopher to extract unknown/multiple props, and flattening the results:

 const { chain, ifElse, is, of, values } = R; const extractAndFlatten = chain(ifElse(is(Date), of, values)); const data = [ new Date("2018-11-20T09:00:00.000Z"), new Date("2018-11-19T09:00:00.000Z"), { "before": new Date("2018-12-14T00:00:00.000Z") } ]; console.log(extractAndFlatten(data)); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script> 

Answer 2

In case you want plain Javascript solution.

Assumption - Objects are nested to 1 level as seen in OP

 var arr = [ "2018-11-20T09:00:00.000Z", "2018-11-19T09:00:00.000Z", { "before": "2018-11-14T00:00:00.000Z" } ] var result = arr.map(d => typeof d == "object" ? Object.values(d) : d) console.log(result.flat()) 

Answer 3

https://ramdajs.com/docs/#map

Here's a repl , and the code :

let arr = [
"2018-11-20T09:00:00.000Z",
"2018-11-19T09:00:00.000Z",
{
  "before": "2018-11-14T00:00:00.000Z"
}
];

R.map((item) => item.before || item, arr);