jQuery $.each() not saving changes

by fiddleyetu

HTML

<span id="source"></span><br /><br />
<button onclick="doReplace()" 
    title="Replace all change with done">
    Replace
</button><br /><br />
<span id="result"></span>
<div id="debug"></div>

CSS

span { color: Blue; }

JavaScript

//basic custom object with two properties
var obj = { 
    testA: "please change this",
    testB: "and change this too" 
};

//display original text
$(document).ready(function() {
    $("#source").text("Source: " + obj.testA + " + " + obj.testB);
});

//search/replace properties and display result
function doReplace() {
    $.each(obj, function (key, value) {
        $('#debug').append( '<br><br><b>key = ' + key + '; value = "' + value + '"</b><br>')
        .append( '<br>Equality TEST: ' + (this == value) )
        .append( '<br>Output TEST - using value: ' + value.replace('change','done') )
        .append( '<br>Output TEST - using "this": ' + this.replace('change','done') );
        obj[ key ] = this.replace('change','done');
    });
    $("#result").text("Result: " + obj.testA + " + " + obj.testB);
}