Format data in javascript

Can be done easily using reduce

PS: Please also provide your attempt when you ask questions here. It'll help us help you better. Thanks

var input = [{
 date: "2021-02-09",
 value: 1,
 user: "Internal"
 },
 {
 date: "2021-02-09",
 value: 1,
 user: "External"
 },
 {
 date: "2021-02-12",
 value: 2,
 user: "Internal"
 },
 {
 date: "2021-02-12",
 value: 1,
 user: "External"
 },
 {
 date: "2021-02-14",
 value: 0,
 user: "External"
 },
 {
 date: "2021-02-14",
 value: 2,
 user: "Internal"
 }
];
var output = input.reduce((acc, curr) => {
 var existingIndex = (acc || []).findIndex(
 (entry) => entry.date === curr.date
 );
 if (existingIndex !== -1) {
 // Only update the entry
 acc[existingIndex].value += curr.value;
 acc[existingIndex][curr.user] += curr.value;
 } else {
 // Insert new entry
 acc.push({
 date: curr.date,
 Internal: curr.user === "Internal" ? curr.value : 0,
 External: curr.user === "External" ? curr.value : 0,
 value: curr.value
 });
 }
 return acc;
}, []);
console.log(output)

You can loop over data like this and filter out the dates and the internal external counts based on your calculations in a new array

const sampleData = [{
 "date": "2021年02月09日",
 "value": 1,
 "user": "Internal"
 },
 {
 "date": "2021年02月09日",
 "value": 1,
 "user": "External"
 },
 {
 "date": "2021年02月12日",
 "value": 2,
 "user": "Internal"
 },
 {
 "date": "2021年02月12日",
 "value": 1,
 "user": "External"
 },
 {
 "date": "2021年02月14日",
 "value": 0,
 "user": "External"
 },
 {
 "date": "2021年02月14日",
 "value": 2,
 "user": "Internal"
 }
];
let formattedData = [];
sampleData.forEach(item => {
 const itemIndex = formattedData.findIndex(newItem => newItem.date === item.date);
 const internalCount = item.user === "Internal" ? item.value : 0;
 const externalCount = item.user === "External" ? item.value : 0;
 if (formattedData.length === 0 || itemIndex === -1)
 formattedData.push({
 date: item.date,
 internal: internalCount,
 external: externalCount,
 total: internalCount + externalCount
 });
 else {
 formattedData.splice(itemIndex, 1, {
 date: item.date,
 internal: formattedData[itemIndex].internal + internalCount,
 external: formattedData[itemIndex].external + externalCount,
 total: formattedData[itemIndex].total + internalCount + externalCount
 });
 }
});
console.log(formattedData);

• javascript
• format