Stroke left and right side of rect svg
It's another hack, but you can add a filter to your shape and clip the top and bottom by your strokewidth - which here I'm assuming is 1 unit.
<defs>
<filter id="clippy" x="0" y="1" height="248" width="356">
<feColorMatrix type="identity"/>
</filter>
</defs>
<rect filter="url(#clippy)" class="extent" width="356" height="250"
style="cursor: move;opacity: 0.2; fill: #FF9000;" x="578"></rect>
Update:
Here is the d3.js version of the answer created by Christopher Chiche (see original lower down):
svg.append("defs").append("filter")
.attr("id", "clippy")
.attr("x", "0")
.attr("y", "1")
.attr("height", "248")
.attr("width" "356")
.append("feColorMatrix")
.attr("type", "identity")
svg.append("rect")
.attr("filter", "url(#clippy)")
.attr("class", "extent")
.attr("style", "cursor:move; opacity:0.2; fill: #FF9000")
.attr("x", "578")
.attr("height", "250")
.attr("width" "356")
Here is the d3.js
version of the answer posted by Michael Mullany. If you think of accepting my answer, please accept his instead. I just did this as an exercise to have fun:
svg.append("defs").append("filter")
.attr("id", "clippy")
.attr("x", "0")
.attr("y", "1")
.attr("height", "248")
.attr("width" "356")
.append("feColorMatrix")
.attr("type", "identity")
svg.append("rect")
.attr("filter", "url(#clippy)")
.attr("class", "extent")
.attr("style", "cursor:move; opacity:0.2; fill: #FF9000")
.attr("x", "578")
.attr("height", "250")
.attr("width" "356")