javaScript でhtmlの<img> タグのソースパスをreplace（）したい。

自分が達成したいことは、htmlの<section class = "film">の子である<p>の子のすべての<img>のソースパスを取得して、そのソースパスの最初の”images”をJavaScript のreplace()で"reviews"に変え、そして例えば、
<img src="images/Gone_With_the_Wind.jpg"の"jpg"を”xml”に変えたいのですが、**var finalXml = xmlName.replace("images","reviews");**このようにすると replace is not a functionと出てエラーになってしまいます。どうしたらreplace を使えるようになるのでしょうか？？

```javaScript

/**

Created by tkimura on 8/16/17.

var Reviews = (function(){
var pub = {};

function showReviews(){
    var target = $(this).parent().find(".review")[0];
    var xmlName = $(this).parent().find("img")[0];
    var finalXml = xmlName.replace("images", "reviews");
    console.log(finalXml);







}

pub.setup = function(){
    $('.film').append("<input type='button' class='showReviews' value='Show Reviews'>", "<div class='review'></div>");

    $(".showReviews").click(showReviews);
}

return pub;

}());

$(document).ready(Reviews.setup);



var target = $(this).parent().find(".review")[0];
        var xmlName = $(this).parent().find("img")[0];
     **var finalXml = xmlName.replace("images","reviews");**


```HTML
<!DOCTYPE html>

<html lang="en">

    <head>
        <title>Classic Cinema</title>
        <link rel="stylesheet" href="style.css">
        <meta charset="utf-8">
		<script src="showHide.js"></script>
        <script src="cookies.js"></script>
        <script src="cart.js"></script>
        <script src = "jquery-3.2.1.min.js"></script>
        <script src="showReviews.js"></script>
    </head>

    <body>

        <header>
            <h1>Classic Cinema</h1>
        </header>

		<div id="user">
            <div id="login">
                <form id="loginForm">
                    <label for="loginUser">Username: </label>
                    <input type="text" name="loginUser" id="loginUser">
                    <label for="loginPassword">Password: </label>
                    <input type="password" name="loginPassword" id="loginPassword">
                    <input type="submit" id="loginSubmit" value="Login">
                </form>
            </div>

            <div id="logout">
                <p>Welcome, <span id="logoutUser"></span></p>
                <form id="logoutForm">
                    <input type="submit" id="logoutSubmit" value="Logout">
                </form>
            </div>
		</div>

        <nav>
            <ul>
                <li> <a href="index.html">Home</a>
                <li> Classics
                <li> <a href="scifi.html">Science Fiction and Horror</a>
                <li> <a href="hitchcock.html">Alfred Hitchcock</a>
				<li> <a href="checkout.html">Checkout</a>
            </ul>
        </nav>


        <div id="main">
            <h2>Classic Films</h2>

            <section class="film">
                <img src="images/Gone_With_the_Wind.jpg" alt="Gone With the Wind">
                <h3>Gone With the Wind (1939)</h3>
                <p>Directed by: Victor Fleming, George Cukor, Sam Wood</p>
                <p>Starring: Clark Gable, Vivien Leigh, Leslie Howard, Olivia de Havilland, Hattie McDaniel</p>
                <p>An epic historical romance and winner of 8 Academy Awards (from 13 nominations).</p>
                <p>
                $<span class="price">13.99</span>
                <input type="button" value="Add to Cart" class="buy">
                </p>
            </section>

            <section class="film">
                <img src="images/The_Jazz_Singer.jpg" alt="The Jazz Singer">
                <h3>The Jazz Singer (1927)</h3>
                <p>Directed by: Alan Crosland</p>
                <p>Starring: Al Jolson, May McAvoy, Warner Oland, Cantor Rosenblatt</p>
                <p>The first feature length 'talkie', The Jazz Singer is a piece of cinematic history</p>
                <p>
                $<span class="price">13.99</span>
                <input type="button" value="Add to Cart" class="buy">
                </p>
            </section>

            <section class="film">
                <img src="images/Metropolis.jpg" alt="Metropolis">
                <h3>Metropolis (1927)</h3>
                <p>Directed by: Fritz Lang</p>
                <p>Starring: Alfred Abel, Brigitte Helm, Gustav Fr&ouml;hlich, Rudolf Klein-Rogge</p>
                <p>A lovingly restored version of Fritz Lang's dystopian masterpiece, one of the great achievements of the silent era.</p>
                <p>
                $<span class="price">19.99</span>
                <input type="button" value="Add to Cart" class="buy">
                </p>
            </section>

        </div>

        <footer>
            <p>
            Classic Cinema is not a real store. No products are available, and no money will be accepted.
            <p>
            All images from <a href="http://commons.wikimedia.org/wiki/Main_Page">Wikimedia Commons</a> and are believed to be in the public domain.
            </p>
        </footer>

    </body>
</html>