const data = [
{
id: "1",
name: "Battery A",
intervals: [
{
timestamp: 1635757200,
kwh: 20
},
{
timestamp: 1635758100,
kwh: 30
},
{
timestamp: 1635759000,
kwh: 35
},
{
timestamp: 1635759900,
kwh: 37
},
{
timestamp: 1635760800,
kwh: 38
},
{
timestamp: 1635761700,
kwh: 45
},
{
timestamp: 1635762600,
kwh: 52
},
{
timestamp: 1635763500,
kwh: 55
},
{
timestamp: 1635764400,
kwh: 60
},
{
timestamp: 1635765300,
kwh: 65
}
]
}]
let y = {
timestamp: 1635765300,
kwh: 75
}
let result = data.map(a => a.intervals);
let z = data[0]['intervals'].concat(y)
let a = [...data, data[0]['intervals'].y]
console.log(a)