JSFiddle - React, Tailwind, and code Playground

HTML

<div id="myelement" min="0.5" step="0.75"></div>

JavaScript

// reference your element
var myelement = document.getElementById('myelement');

// just for testing, show the original attributes
myelement.insertAdjacentHTML('beforeend', "<b>Original values</b>");
myelement.insertAdjacentHTML('beforeend', "<br>Min: "+ myelement.getAttribute("min"));
myelement.insertAdjacentHTML('beforeend', "<br>Step: "+ myelement.getAttribute("step"));

// remove the existing ones
myelement.removeAttribute("min");
myelement.removeAttribute("step");

// create new ones
var min = document.createAttribute('min');
var step = document.createAttribute('step');

// give the new ones a value
min.value = '100'; //put your new values here
step.value = '100'; //put your new values here

// re-add the attributes
myelement.setAttributeNode(min);
myelement.setAttributeNode(step);

// just for testing, show the changed attributes
myelement.insertAdjacentHTML('beforeend', "<hr><b>New values</b>");
myelement.insertAdjacentHTML('beforeend', "<br>Min: "+ myelement.getAttribute("min"));
myelement.insertAdjacentHTML('beforeend', "<br>Step: "+ myelement.getAttribute("step"));