Add onclick event to SVG element

It appears that all of the JavaScript must be included inside of the SVG for it to run. I was unable to reference any external function, or libraries. This meant that your code was breaking at svgstyle = svgobj.getStyle();

This will do what you are attempting.

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg xmlns='http://www.w3.org/2000/svg' version='1.1' height='600' width='820'>

  <script type="text/ecmascript"><![CDATA[
      function changerect(evt) {
        var svgobj=evt.target;
        svgobj.style.opacity= 0.3;
        svgobj.setAttribute ('x', 300);
      }
    ]]>
  </script>

  <rect onclick='changerect(evt)' style='fill:blue;opacity:1' x='10' y='30' width='100'height='100' />
</svg>

Demo in JSFiddle

    var _reg = 100;
    var _l = 10;

    // Create PATH element
    for (var x = 1; x < 20; x++) {
        var pathEl = document.createElementNS("http://www.w3.org/2000/svg", "path");
        pathEl.setAttribute('d', 'M' + _l + ' 100 Q 100  300 ' + _l + ' 500');
        pathEl.style.stroke = 'rgb(' + (_reg) + ',0,0)';
        pathEl.style.strokeWidth = '5';
        pathEl.style.fill = 'none';
        $(pathEl).mousemove(function(evt) {
            $(this).css({ "strokeWidth": "3", "stroke": "#ff7200" })
                .hide(100).show(500).css({ "stroke": "#51c000" })
        });

        $('#mySvg').append(pathEl);
        _l += 50;
    }

If you don't need to click specific parts of the svg this might be a possible solution:

Put a div on top and add events to that div. z-index is not needed if the svg element is before the div tag in the html structure.

HTML

<div class='parent'>
  <div class='parent-events'></div>
  <div class='my-svg'><svg></svg></div>
</div>

CSS

.parent {
  position: relative;
}

.my-svg {
  position: relative;
  z-index: 0;
}

.parent-events {
  position: absolute;
  width: 100%;
  height: 100%;
  z-index: 1
}

Javascript

const eventArea = document.querySelector('.parent-events');
eventArea.addEventListeners('click', () => {
  console.log('clicked');
});