How can I extract all the numbers from this JSON in a set, in JavaScript?
[
{
"name": "list0",
"list": [0,1,2,3,4]
},
{
"name": "list1",
"list": [3,4,5,6,7,8,9]
}
]
I'd like to get a set with only:
0,1,2,3,4,5,6,7,8,9
-
Does this answer your question? Concatenate multiple array of objects into one and use outside of functionHeretic Monkey– Heretic Monkey2020-07-13 14:49:29 +00:00Commented Jul 13, 2020 at 14:49
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4 Answers
You can try using Set()
The
Setobject lets you store unique values of any type, whether primitive values or object references.
and flatMap()
The
flatMap()method first maps each element using a mapping function, then flattens the result into a new array. It is identical to a map() followed by a flat() of depth 1, butflatMap()is often quite useful, as merging both into one method is slightly more efficient.
var arr = [
{
"name": "list0",
"list": [0,1,2,3,4]
},
{
"name": "list1",
"list": [3,4,5,6,7,8,9]
}
]
var res = [... new Set(arr.flatMap(el => el.list))];
console.log(res);
Comments
You can use array.reduce and spread operator:
let input = [
{
"name": "list0",
"list": [0,1,2,3,4]
},
{
"name": "list1",
"list": [3,4,5,6,7,8,9]
}
];
let numbers = input.reduce((acc,cur) => [...acc, ...cur.list], []);
console.log(numbers);
console.log(...new Set(numbers))
Comments
you could use map and flat to iterate through the array and convert it to one level array or flatmap to do both at the same time and then you use Set to deduplicate
array=[ { "name": "list0", "list": [0,1,2,3,4] }, { "name": "list1", "list": [3,4,5,6,7,8,9] } ]
set=[...new Set(array.map(x=>x.list).flat())]
console.log(set)using flatmap()
array=[ { "name": "list0", "list": [0,1,2,3,4] }, { "name": "list1", "list": [3,4,5,6,7,8,9] } ]
set=[...new Set(array.flatMap(x=>x.list))]
console.log(set)
Comments
You can use the spread ...array operator to solve the problem.
let arr = [
{
"name": "list0",
"list": [0,1,2,3,4]
},
{
"name": "list1",
"list": [3,4,5,6,7,8,9]
}
]
let a = [];
arr.forEach(obj=>{
a.push(...obj.list)
})
const set = new Set([...a]);
console.log(...set)