Edit in JSFiddle

visualize({
    auth: {
        name: "superuser",
        password: "superuser"
    }
}, function (v) {
    
    var report,
        zoom = 1,
        plus = document.getElementById("plus"),
        minus = document.getElementById("minus"),
        width = document.getElementById("width"),
        height = document.getElementById("height"),
        page = document.getElementById("page");
    
    report = v.report({
        resource: "/public/Samples/Reports/AllAccounts",
        container: "#container",
        success: function () {
            plus.removeAttribute("disabled");
            minus.removeAttribute("disabled");
            width.removeAttribute("disabled");
            height.removeAttribute("disabled");
            page.removeAttribute("disabled");
        },
        error: function (err) {
            alert(err.message);
        }
    });
    
    plus.onclick = function () {
        report
            .scale(zoom += 0.1)
            .render();
    }
    
    minus.onclick = function () {
        report
            .scale((zoom -= 0.1) > 0 ? zoom : zoom = 0.1)
            .render();
    }
    
    width.onclick = function () {
        report
            .scale("width")
            .render();
    }
    
    height.onclick = function () {
        report
            .scale("height")
            .render();
    }
    
    page.onclick = function () {
        report
            .scale("container")
            .render();
    }
});

<script type="text/javascript" src="http://visualizejs-preview.eng.jaspersoft.com:8080/jasperserver-pro-branch/client/visualize.js"></script>
<div>
    <button id="plus" disabled>+</button>
    <button id="minus" disabled>-</button>
    <button id="width" disabled>Fit Width</button>
    <button id="height" disabled>Fit Height</button>
    <button id="page" disabled>Fit Page</button>
</div>
<div id="container"></div>

li {
    border: thin solid red;
    list-style: none;
}