How to check if svg has a fill-opacity versus a fill-opacity of 0?

Question

Suppose I want to check the fill-opacity of a SVG element. I'd do this

elem.attr('fill-opacity');

This can give me back 0 if the element has no fill-opacity attribute or if the fill-opacity has been set to 0.

How do I distinguish between those two cases?

Are you sure it gives back 0 if the element has no fill-opacity attribute? [This answer](https://stackoverflow.com/questions/1318076/jquery-hasattr-checking-to-see-if-there-is-an-attribute-on-an-element) leads me to believe it would return either `undefined` or `false`. — Maximillian Laumeister, Aug 28 '15 at 23:05

score 2 · Answer 1 · answered Aug 29 '15 at 02:59

2

Can't you simply use elem.hasAttribute?

answered Aug 29 '15 at 02:59

Nick Ooms

21
1

It's just rhetorical. – Robert Longson Aug 29 '15 at 10:08

score 1 · Answer 2 · answered Aug 29 '15 at 02:51

If fill-opacity is not specified, attr() returns undefined.

alert("fill-opacity (DOM) ="+document.getElementById("test").getAttribute("fill-opacity"));
alert("fill-opacity (jQuery) ="+$("#test").attr("fill-opacity"));

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<svg>
  <rect id="test" width="10" height="10"/>
</svg>

How to check if svg has a fill-opacity versus a fill-opacity of 0?

2 Answers2