如何使用 ramda 获取对象中的所有值

Question

how do you map to all the object and get all the value using ramda

const input ={
  a: 'apple',
  b:{
    c:{
      d:{
        e: 'egg',
        f: 'fish'
      }
    },
    g: 'guava',
    h: 'honey',
  }
}

console.log :

['apple',
'egg',
'fish',
'guava',
'honey']

Answer 1

You can use Object.values() , and Array.flatMap() to create a recursive function that gets the values from an object, and then iterates the values, and calls itself on every value that is an object:

 const getDeepValues = obj => Object .values(obj) .flatMap(v => typeof v === 'object' ? getDeepValues(v) : v) const input = {"a":"apple","b":{"c":{"d":{"e":"egg","f":"fish"}},"g":"guava","h":"honey"}} const result = getDeepValues(input) console.log(result)

You can create a pointfree function with Ramda, that does the same thing:

1. Get the values,
2. Use R.When with R.is(Object) to check if the value is an object, and call getDeepValues on the value if it is (the arrow function is needed because the getDeepValues is not declared yet), or return the value if it's not.

 const { pipe, values, chain, when, is } = R const getDeepValues = pipe( values, // get the values chain(when(is(Object), v => getDeepValues(v))) // if the value is an object use getDeepValues or just return the value ) const input = {"a":"apple","b":{"c":{"d":{"e":"egg","f":"fish"}},"g":"guava","h":"honey"}} const result = getDeepValues(input) console.log(result)

 <script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.js"></script>

Answer 2

No need to use Ramda, you can do it in plan JS in one cleverly-written recursive reduce :

 const getDeepValues = obj => Object .values(obj) // 1. iterate over the object values .reduce((acc, cur) => [ ...acc, // 3. pass previous values ...( cur instanceof Object // 4. if the value we encounter is an object... ? getDeepValues(cur) // ...then use recursion to add all deep values : [cur] // ...else add one string ), ], []); // 2. start with an empty array const input ={ a: 'apple', b:{ c:{ d:{ e: 'egg', f: 'fish' } }, g: 'guava', h: 'honey', } } console.log(getDeepValues(input))