JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://documentcloud.github.com/underscore/underscore.js"></script>

JavaScript

var data = [
    {name: 'bar', surname: 'foo'}, 
    {name: 'secondBar', surname: 'secondFoo'}
];

_.each(data, function(obj) {
    var objCopy = obj;
    objCopy.name = 'changed';
    document.write(objCopy.name + "<br />");
});

_.each(data, function(obj) {
    document.write(obj.name + "<br />");
});