const {
deepEntries, deepEntriesIterator,
delimitEntry, delimitEntryBy,
rotateEntry, rotateEntryBy
} = require('deep-entries@4.0.0')
A shape made up of both Objects or Arrays can be described in terms of deep entries. Only enumerable own-members will be returned and iteration will honour index and / or insertion order. The following examples will consume this input:
const input = {
foo: 1,
bar: {
deep: {
key: 2
}
},
baz: [
3,
[4,5],
{
key: 6
}
]
}
deepEntries(): Similiar to Object.entries() will return nested entries as arrays of varying length, with the value always trailing.
deepEntries(input)
deepEntries(): Will accept an optional map function as a second parameter.
// delimitEntry is shorthand for delimitEntryBy('.')
deepEntries(input, delimitEntry)
deepEntries() is an alias that collects all entries from a deepEntriesIterator(), which is also exposed to aid in performant iteration of larger structures. The rotateEntry map function rotates the entry array by 1 (i.e. putting the value first), allowing for more convenient destructuring of an entry.
// rotateEntry is shorthand for rotateEntryBy(1)
for(let [value, ...keys] of deepEntriesIterator(input, rotateEntry)) {
console.log({ keys, value })
}
It's worth noting that objects can have assigned iterators too.
const { withIterator } = require('with-iterator')
const withDeepEntriesIterator = withIterator(function*() {
yield* deepEntriesIterator(this, delimitEntryBy(':'))
})
withDeepEntriesIterator(input)
Array.from(input)
The map functions passed to deepEntries() and deepEntriesIterator() can effectively filter entries by not returning them - i.e. returning "undefined".
const { last: getValue } = require('ramda')
deepEntries(input, entry =>
getValue(entry) > 3 ? entry : undefined
)
The map functions follow a pattern of returning "undefined" if passed "undefined" such that they may be composed with filters, without throwing errors.
const { pipe } = require('ramda')
const atDepth = n => entry => {
if (entry.length === 2 + n) return entry
}
deepEntries(input, pipe(
atDepth(1),
delimitEntry
))
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