I have an array of object.structure is like that.
animal = [{"cow":{"leg":4,"eye":2}},{"monkey":{"leg":2,"eye":2}}]
here first key is dynamic like cow and monkey
so my question is how can i access the key leg if first key is dynamic
6 Answers
If you are sure that each object within the array has only 1 property (which would be the type of animal), you can do something like this.
animals = [{"cow":{"leg":4,"eye":2}},{"monkey":{"leg":2,"eye":2}}];
for (let animal of animals) {
let propName = Object.keys(animal)[0];
let result = animal[propName];
console.log(result); // <- Do what you want with it
}3 Comments
David Fontes
@TylerRoper Thank you, I made it as an inline snippet as you suggested. Also, with the array supplied it works, however I will try to come up with a better solution.
David Fontes
@vivek_23 I'm not iterating over the array with
Object.keys(), I'm only using it to get the keys of each animal.
mighty_dev
@DavidFontes Ahh!! Overlooked that.
You can use the newly added Object.entries, which make the most sense imo.
Thus for your data you have:
const animal = ...
for (a of animal) {
const [animalName, animalDesc] = Object.entries(a)[0]; // assumes there is only one
}
Comments
This will give you an array of objects with the contents of each animal.
animals.map(animal => animal[Object.keys(animal)[0]]);
Comments
1) Find an animal with that key
2) Return it with [animal]
3) Use it as you would (.leg)
const animals = [{ cow: { leg: 4, eye: 2 } }, { monkey: { leg: 2, eye: 2 } }];
const animal = 'cow';
const leg = animals.find(a => !!a[animal])[animal].leg;
answered Jul 24, 2019 at 14:14
Roberto Zvjerković
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Comments
Maybe convert it into a "non-dynamic-key" object?
const animal = [{"cow":{"leg":4,"eye":2}},{"monkey":{"leg":2,"eye":2}}]
const newanimal = animal.map(obj => {
const keys = Object.keys(obj)
return keys.map(key => ({ key, value: obj[key] }))
}).flat(Math.Infinity)
console.log(newanimal)2 Comments
mehulmpt
@TylerRoper thanks for the hint! or I could flatten the array using
flat
Tyler Roper
You can, although you're using an additional iteration (
map -> flat) as opposed to a single flatMap. Not sure what the efficiency difference would be though so it may be negligible.You can use map & Object.keys. map will return a new array. Object.keys is use to get all the keys inside each of the object in animal array.Then this line elem[getKeys].leg will retrieve the value of the leg key
let animal = [{
"cow": {
"leg": 4,
"eye": 2
}
}, {
"monkey": {
"leg": 2,
"eye": 2
}
}];
let legVal = animal.map((elem) => {
let getKeys = Object.keys(elem)[0];
return elem[getKeys].leg
})
console.log(legVal)
Object.keys()and, for each one, check if the key's value containsleg. Or, if it will only ever be one key, no need to loop; you can just doObject.keys(obj)[0]to get the first key. Or, better yet, if you don't actually need the key name and just want to know iflegexists, useObject.values(obj)[0].leg.