I have array of the following form:
[
{key: "key1", value: value1}
{key: "key2", value: value2}
{key: "key3", value: value3}
...
]
I need to convert to the following form:
{ { key1 : value1}, { key2 : value2}, { key3 : value3} }
How to do it with reduce() ?
I am trying to use this code:
var someObject = this.someArray.reduce(function(acc, item) {
return { [item.key]: item.value};
}, {});
but I always get only the last item instead of all of them.
The issue is in your return
return acc + { [item.key]: item.value};
You cannot use the + operator to add objects. Try the following:
acc[item.key] = item.value;
return acc
This assumes your keys are all unique. See full example below:
let x = [{
key: "key1",
value: 'value1'
},
{
key: "key2",
value: 'value2'
},
{
key: "key3",
value: 'value3'
},
].reduce((accumulatedValue, curentValue) => {
accumulatedValue[curentValue.key] = curentValue.value;
return accumulatedValue
}, {})
console.log(x);
Element implicitly has an 'any' type because expression of type 'string' can't be used to index type '{}'.
{} as Record<string, string> at the end ....Either you seek an array of object, then the following example applies :
const res = [{
key: 'key1',
value: 'value1',
}, {
key: 'key1',
value: 'value1',
}, {
key: 'key1',
value: 'value1',
}].reduce((tmp, {
key,
value,
}) => [
...tmp,
{
[key]: value,
},
], []);
console.log(res);Either you seek an unique object, then the following example applies :
const res = [{
key: 'key1',
value: 'value1',
}, {
key: 'key2',
value: 'value2',
}, {
key: 'key3',
value: 'value3',
}].reduce((tmp, {
key,
value,
}) => ({
...tmp,
[key]: value,
}), {});
console.log(res);About your code, as people told you already in the comments, you cannot simply use the + operator to concatenate either arrays or objects.
+ from the code in question. it was a mistake. look now.
... is called the spread operator, what I do is creating a new array composed of all the elements from the accumulator plus a new element. It have the same result as using assignation (like Dane Brouwer answer). here is some tutorial
+on objects coerces them to strings"[object Object]". It's unclear how you thought that might work."[object Object][object Object][object Object][object Object]".