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SUM AND GROUPING JSON DATA USING JAVASCRIPT [duplicate]

This question already has answers here:
How to group by and sum an array of objects? [duplicate]
(2 answers)
Sum JavaScript object propertyA values with the same object propertyB in an array of objects
(12 answers)
Group by, and sum, and generate an object for each array in JavaScript
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ES6 Implementation of Group By and SUM
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Javascript array of objects group and sum items
(4 answers)
Closed last year.
Sorry if this has been asked before, but I couldn't find a good example of what I'm trying to accomplish. Maybe I'm just not searching for the right thing. Please correct me if there's an explanation of this somewhere.
so let's says I have a data like this :
data = [
{"no":1,"location":"New York","transaction":3000},
{"no":2,"location":"Tokyo","transaction":3000},
{"no":3,"location":"New York","transaction":3000},
{"no":4,"location":"Amsterdam","transaction":3000},
{"no":5,"location":"Manchester","transaction":3000},
{"no":6,"location":"New York","transaction":3000},
{"no":7,"location":"Tokyo","transaction":3000},
{"no":8,"location":"Tokyo","transaction":3000},
{"no":9,"location":"New York","transaction":3000},
{"no":10,"location":"Amsterdam","transaction":3000}
]
what i wanted to is an output like this :
result = [
{"location":"New York","transaction":12000},
{"location":"Tokyo","transaction":9000},
{"location":"Amsterdam","transaction":6000}
{"location":"Manchester","transaction":3000}
]
so what i wanted to do is grouping the data based on location and sum the transaction where the location is same and push the data to another array. i don't know where to start, need some help to solve this or any suggestion to solve this using Javascript. thank you

Working Demo :
// Input array
const data = [
{"no":1,"location":"New York","transaction":3000},
{"no":2,"location":"Tokyo","transaction":3000},
{"no":3,"location":"New York","transaction":3000},
{"no":4,"location":"Amsterdam","transaction":3000},
{"no":5,"location":"Manchester","transaction":3000},
{"no":6,"location":"New York","transaction":3000},
{"no":7,"location":"Tokyo","transaction":3000},
{"no":8,"location":"Tokyo","transaction":3000},
{"no":9,"location":"New York","transaction":3000},
{"no":10,"location":"Amsterdam","transaction":3000}
];
// result array
const resultArr = [];
// grouping by location and resulting with an object using Array.reduce() method
const groupByLocation = data.reduce((group, item) => {
const { location } = item;
group[location] = group[location] ?? [];
group[location].push(item.transaction);
return group;
}, {});
// Finally calculating the sum based on the location array we have.
Object.keys(groupByLocation).forEach((item) => {
groupByLocation[item] = groupByLocation[item].reduce((a, b) => a + b);
resultArr.push({
'location': item,
'transaction': groupByLocation[item]
})
})
console.log(resultArr)

JavaScript array manipulation interview question [duplicate]

This question already has answers here:
Merge objects with same id in array
(7 answers)
Closed 1 year ago.
This is a question that I have encountered during an interview:
Write a function to transform the array:
[
{name:'a',values:[1,2]},
{name:'b',values:[3]},
{name:'a',values:[4,5]}
]
to:
[
{name:'a',values:[1,2,4,5]},
{name:'b',values:[3]}
]
I know this is not hard, but I just can't figure it out.
Does anyone know how to solve it?
Are there any places that I can find and practice more practical questions like this one?

You can group the array by name and then get an array using the grouped object:
const bla = [
{name:'a',values:[1,2]},
{name:'b',values:[3]},
{name:'a',values:[4,5]}
];
const res = Object.values(bla.reduce((obj, { name, values }) => {
obj[name] = obj[name] ?? {name, values: []}
obj[name].values.push(...values)
return obj
}, {}));
console.log(res)

Turn array with two elements into JS object with one k/v-pair [duplicate]

This question already has answers here:
Creating object with dynamic keys [duplicate]
(2 answers)
Closed 2 years ago.
I have this array: ["description", "asc"]
and want to turn it into this object:
{ "description": "asc" }
What's the fastest way to achieve this?
I tried
const obj = { array[0] : array[1] }
But it doesn't work because I can't seem to set the key of the object dynamically?

you can try this
const array = new Map([
["description", "asc"]
]);
const convobj = Object.fromEntries(array);
console.log(convobj)

You can do this:
let array = ["description", "asc"];
const obj = { [array[0]]: array[1] };
console.log(obj);

You can try this:
const bar = {
[array[0]]: array[1]
}

JSON object string to convert an array using map [duplicate]

This question already has answers here:
Merge multiple objects inside the same array into one object [duplicate]
(2 answers)
Closed 3 years ago.
Here is my response from my server.
var my_array = [{"1":"1"},{"2":"8"},{"4":"13"},{"5":"19"},{"6":"22"}]; //from server
I want to convert it like
var new_array = { 1 : "1", 2 : "8", 4 : "13", 5 : "19" , 6 : "22"}
But how to convert it using map function
new_array = my_array.map(function (a) {
return ???
});

Use reduce with spreading - you can't map an array to an object. Spreading also allows for multiple properties in each object.
var new_array = my_array.reduce((a, c) => ({ ...a, ...c }), {});
You could also use Object.fromEntries after flatMapping the entries:
var new_array = Object.fromEntries(my_array.flatMap(Object.entries));

Convert array to object with key and value in javascript [duplicate]

This question already has answers here:
Convert an array to an array of objects
(4 answers)
Closed 5 years ago.
How covert or add array elements into object.
Now
arr = [
["1/1/2017",113],
["3/11/2017",58],
["3/12/2017",70],
["3/13/2017",76]
]
Should be
arr = [
{date:"1/1/2017", count:113},
{date:"3/11/2017", count:58},
{date:"3/12/2017", count:70},
{date:"3/13/2017", count:76}
]

arr.map(function(arr1) {
return {
date : arr1[0],
count : arr1[1]
}
})