A nice way to nullify CSS transforms and get original positions of the un-modified rect

nullify-transforms.js

// Nullify the transforms of the element
// 
// This is all behaving just like getBoundingClientRect() but it nullifies all the transforms
// and kinds _reverts_ the element onto its original position.
// This will work even with complex translations, rotations.
// The beauty is in the way it applies matrix inverse onto the transformation
// matrix and mutates the getboundingclientrect along the way.
//
// Usage:
// let { top, left } = nullifyTransforms(el);
// 
// TODO:
// can probably be extended to be having width/height support too but
// that is not mandatory, I only needed top/left for my use case
//
// Props to that awesome answer on StackOverflow
// https://stackoverflow.com/questions/27745438/how-to-compute-getboundingclientrect-without-considering-transforms
function nullifyTransforms(el) {
	//add sanity checks and default values

	let {top, left, width, height} = el.getBoundingClientRect()
	let transformArr = parseTransform(el)

	if (transformArr.length == 6) {
		// 2D matrix
		// need some math to apply inverse of matrix
		// That is the matrix of the transformation of the element
                // a scale x
                // b shear y
                // c shear x
                // d scale y
                // e translate x
                // f translate y
		var t = transformArr
		let det = t[0] * t[3] - t[1] * t[2]

		return {
			width: width / t[0],
			height: height / t[3],
			left:
				(left * t[3] - top * t[2] + t[2] * t[5] - t[4] * t[3]) /
				det,
			top:
				(-left * t[1] + top * t[0] + t[4] * t[1] - t[0] * t[5]) /
				det,
		}
	} else {
		/*if (transformArr.length > 6)*/
		//3D matrix
		//haven't done the calculation to apply inverse of 4x4 matrix
		return {top, left, width, height}
	}

	function parseTransform(el) {
		let transform = window.getComputedStyle(el).transform

		//add sanity check
		return transform
			.split(/\(|,|\)/)
			.slice(1, -1)
			.map(function(v) {
				return parseFloat(v)
			})
	}
}

Never mind, just found out about .offsetLeft and .offsetTop ;)