javascript – offsetLeft returning 0 when mum or dad repositioned

I’ve an outer div id='a' and an interior div id='b'.

<div id="a">
  <div id="b">hey</div>
</div>

After I set the outer div place to absolute and reposition it, the interior div returns 0 for offsetLeft. However since setting left ="30vw" makes it farther from the left, I might anticipate it to be a bigger quantity now, not 0.

const interior = doc.getElementById("b");
const outer = doc.getElementById("a");

console.log("offsetLeft of interior begin: " + interior.offsetLeft);
// logging >> offsetLeft of interior begin: 8

outer.model.place = "absolute";
outer.model.left = "30vw";

console.log("offsetLeft of interior: " + interior.offsetLeft);
// logging >> offsetLeft of interior: 0

How do I get the precise pixels from the left?

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