The Element method removeAttribute() removes the attribute with the specified name from the element.
removeAttribute(attrName)attrNameA string specifying the name of the attribute to remove from the element. If the specified attribute does not exist, removeAttribute() returns without generating an error.
None (undefined).
You should use removeAttribute() instead of setting the attribute value to null either directly or using setAttribute(). Many attributes will not behave as expected if you set them to null.
// Given: <div id="div1" disabled width="200px">
document.getElementById("div1").removeAttribute("disabled");
// Now: <div id="div1" width="200px">