html

<svg
  xmlns="http://www.w3.org/2000/svg"
  viewBox="0 0 250 250"
  width="250"
  height="250">
  <circle
    cx="100"
    cy="100"
    r="50"
    id="el"
    style="border-top: 1px solid blue; color: red;" />
</svg>
<div id="output"></div>

css

#el {
  font-size: 16px;
}

#output {
  white-space: pre-line;
}

js

const element = document.getElementById("el");
const output = document.getElementById("output");

for (const property of element.attributeStyleMap) {
  output.textContent += `${property[0]} = ${property[1][0].toString()}\n`;
}