Вы можете использовать Array.prototype.reduce & Object.entries :
var obj = { "Usa": [{ "period": "2018-11-03T00:00:00.000+0000", "qty": 1 }, { "period": "2018-11-04T00:00:00.000+0000", "qty": 2 }], "india": [{ "period": "2018-19-03T00:00:00.000+0000", "qty": 2 }, { "period": "2018-19-04T00:00:00.000+0000", "qty": 3 }] }
const result = Object.entries(obj)
.reduce((r, [k,v]) => (r[k] = v.map(({period, qty}) => [period, qty]), r),{})
console.log(result)
Несколько простой подход может быть осуществлен через Object.keys
& reduce
:
var obj = { "Usa": [{ "period": "2018-11-03T00:00:00.000+0000", "qty": 1 }, { "period": "2018-11-04T00:00:00.000+0000", "qty": 2 }], "india": [{ "period": "2018-19-03T00:00:00.000+0000", "qty": 2 }, { "period": "2018-19-04T00:00:00.000+0000", "qty": 3 }] }
const result = Object.keys(obj)
.reduce((r, c) => (r[c] = obj[c].map(({period, qty}) => [period, qty]), r),{})
console.log(result)