JSFiddle - React, Tailwind, and code Playground

JavaScript

var fields = ['firstName', 'lastName', 'email'],
oldVals = ['John', 'Doe', 'doe@mail.com'],
newVals = ['Jo','Do','jo@mail.com'];


function createCustomObj(fields , oldVals, newVals){
var obj={};

	fields.forEach( function(f, i){
		obj[f]={};
    obj[f]['oldValue']= oldVals[i];
    obj[f]['newValue']= newVals[i];
});

return obj;

};

console.log(createCustomObj(fields, oldVals, newVals));