How to uppercase Javascript object keys?

Question

Anyone know a good way to turn this?:

var obj = [{key1: value1,key2: value2},{key3: value3,key4: value4}];

into:

var obj = [{Key1: value1,Key2: value2},{Key3: value3,Key4: value4}];

Answer 1

As of 2019 you can use Object.fromEntries:

let populations = {london: 8.9, beijing: 21.54, mumbai: 18.41};  // March 2020

let entries = Object.entries(populations);
let capsEntries = entries.map((entry) => [entry[0][0].toUpperCase() + entry[0].slice(1), entry[1]]);
let capsPopulations = Object.fromEntries(capsEntries);

console.log(capsPopulations);