After successfully achieving the desired results, here is the data manipulation I have done:
const days = [
{
date: '2016-12-13T00:00:00.000Z',
stats: [
{ name: 'Soft Drinks', sold: 34, },
{ name: 'Snacks', sold: 3, },
{ name: 'Coffee and warm drinks', sold: 26, },
],
},
{
date: '2016-12-14T00:00:00.000Z',
stats: [
{ name: 'Soft Drinks', sold: 34, },
{ name: 'Snacks', sold: 3, },
{ name: 'Coffee and warm drinks', sold: 26, },
],
},
];
const newStats = days.reduce(function (pastDay, currentDay) {
const nextStats = currentDay.stats.map(function(stat) {
const oldSold = pastDay.stats.find(function (old) {
return old.name === stat.name;
});
const newSold = stat.sold + oldSold.sold;
stat.sold = newSold;
return stat;
});
return {
stats: nextStats,
};
});
console.log(newStats);The output I obtained is:
{
"stats": [
{
"name": "Soft Drinks",
"sold": 68
},
{
"name": "Snacks",
"sold": 6
},
{
"name": "Coffee and warm drinks",
"sold": 52
}
]
}
While the initial structure worked perfectly, I encountered an issue when applying the same logic to a different array of objects. The error message "undefined error on pastDay" is appearing. Can someone assist in identifying the problem or suggesting an alternative to the .reduce method?
Below is the array causing the problem:
const days = [
{
"_id":{
"_str":"f23f02994ab992437e423e24"
},
"date":"2016-12-13T00:00:00.000Z",
"statistics":{
"breakdown":{
"byTurnover":[
{
"name":"Soft Drinks",
"sold":34,
"percentage":31.14
},
<snippet shortened for brevity>
],
}
},
"id":{
"_str":"f23f02994ab992437e423e24"
}
},
<snippet shortened for brevity>
{
"_id":{
"_str":"e1906ce07ab811c74528e3cc"
},
"date":"2016-12-15T00:00:00.000Z",
"statistics":{
"breakdown":{
"byTurnover":[
<snippet shortened for brevity>
],
}
},
"id":{
"_str":"e1906ce07ab811c74528e3cc"
}
},
];
const newStats = days.reduce(function (pastDay, currentDay) {
const nextStats = currentDay.statistics.breakdown.byTurnover.map(function(stat) {
const oldSold = pastDay.statistics.breakdown.byTurnover.find(function (old) {
return old.name === stat.name;
});
const newSold = stat.sold + oldSold.sold;
stat.sold = newSold;
return stat;
});
return {
stats: nextStats,
};
});
console.log(newStats);Upon running the code for the second array, the following error was encountered:
Uncaught TypeError: Cannot read property 'breakdown' of undefinedHere is the .reduce code for the second array:
const newStats = days.reduce(function (pastDay, currentDay) {
const nextStats = currentDay.statistics.breakdown.byTurnover.map(function(stat) {
const oldSold = pastDay.statistics.breakdown.byTurnover.find(function (old) {
return old.name === stat.name;
});
const newSold = stat.sold + oldSold.sold;
stat.sold = newSold;
return stat;
});
return {
stats: nextStats,
};
});
console.log(newStats);