JSFiddle - React, Tailwind, and code Playground

JavaScript

var arr = [
  {'David': '1'},
  {'Camilla': '2'},
  {'Sadat': '3'},
  {'Vanuza': '4'}, 
  {'Diego': '5'}
];

function getValueByKey (collection, key) {
	var value;
  collection.map(function (item) {
  	if (key in item) value = item[key];
	})
  
  return value;
}

alert(getValueByKey(arr, 'Camilla'));