Here is the code -
Interface -
interface IWEXInterface {
readonly Date?: string;
"Exec Qty"?: string;
readonly Expiry?: string;
}
Data -
let data: IWEXInterface[] = [
{
Date: "8/30/2021",
"Exec Qty": "13",
Expiry: "17/09/2021",
},
{
Date: "8/30/2021",
"Exec Qty": "15",
Expiry: "17/09/2021",
},
{
Date: "8/30/2021",
"Exec Qty": "13",
Expiry: "17/09/2021",
},
];
Sum and group the objects -
const sums = [
...data
.reduce((map, item) => {
const { Date: key, "Exec Qty": qty } = item;
const prev: IWEXInterface = map.get(key);
if (prev) {
prev["Exec Qty"]! += Number(qty);
} else {
map.set(key, Object.assign({}, item));
}
return map;
}, new Map())
.values(),
];
console.log(sums);
The output -
[ { Date: '8/30/2021', 'Exec Qty': '131513', Expiry: '17/09/2021' } ]
How can I cast the string to number.
Wanted output -
[ { Date: '8/30/2021', 'Exec Qty': 41, Expiry: '17/09/2021' } ]
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try to replace your code with this one, it will return a string but the right one.
if (prev) {
prev["Exec Qty"]! = (Number(prev["Exec Qty"])+ Number(qty)).toString()
} else {
map.set(key, Object.assign({}, item));
}
Just cast prev["Exec Qty"] to number:
prev["Exec Qty"] = String(Number(prev["Exec Qty"]!) + Number(qty));
Perhaps not use the += shorthand?
prev["Exec Qty"] = Number(prev["Exec Qty"]) + Number(qty);