Javascript reduce and map on nested array of objects

Question

i have an array of objects in [ { "country": "USA", "payment": [ { "paymentType": "Visa", "count": 1000 }, { "paymentType": "MasterCard", "count": 1000 } ] }, { "country": "CANADA", "payment": [ { "paymentType": "Visa", "count": 1000 }, { "paymentType": "MasterCard", "count": 1000 } ] }, {...} ] I want to transform it into [ ["USA" , "VISA" , 10000 ], ["USA","Mastercard",1000], [countryName2, paymentType,count] , ... ] Can someone help me>? I tried doing : const data2 = data.map(function(elem) { return [ elem.country, elem.payment.map(b=> b.paymentType), elem.payment.map(c=>c.count), ] }) but the output i get is not what i want, if someone could show how to do it, JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

You can do this with a nested map where each array entry is created by extracting data from payment prefixed with the outer country. const data = [{"country":"USA","payment":[{"paymentType":"Visa","count":1000},{"paymentType":"MasterCard","count":1000}]},{"country":"CANADA","payment":[{"paymentType":"Visa","count":1000},{"paymentType":"MasterCard","count":1000}]}]; const data2 = data.flatMap(({ country, payment }) => payment.map(({ paymentType, count }) => [ country, paymentType, count ]) ); console.log(data2); .as-console-wrapper { max-height: 100% !important; } Run code snippetExpand snippet The flatMap() on the outer map removes the extra level of nesting created in the result.