JSFiddle - React, Tailwind, and code Playground

JavaScript

var data = [{
    thumb: '/images/01.png',
    title: 'My title',
},{
    thumb: '/images/02.png',
    title: 'My title',
},{
    thumb: '/images/03.png',
    title: 'My title',
}];


data.forEach(function(e) {
   e.thumbnail = e.thumb;
   delete e.thumb;    
});

console.log(data);