How do I get the width of an svg element using d3js?

<svg class="svg" height="3300" width="2550">
    <image x="0" y="0" height="3300" width="2550" xlink:href="https://stackoverflow.com/questions/19710174/1.jpg"></image>
    <rect class="word" id="15" x="118" y="259" width="182" height="28"
     text="Substitute"></rect>
</svg>

<script>
    var body = d3.select("body");
    console.log(body);
    var svg = body.select("svg");
    console.log(svg);
    console.log(svg.style("width"));
</script>

Just place your script after svg element is loaded by the browser and all will be fine.