javascript – change surrounding tags for a given text by RegExp

I try to create function that find text in my htmlString (it minify) and then change the tag that wrap the text to h2

 var htmlString = `
<h1>title</h1><p>Lorem ipsum dolor quas!</p><p>Lorem ipsum dolor</p><p>hi</p><p>hi 123</p><div>hi</div><span>Lorem ipsum dolor, sit.</span>
`
const changeTagByText = (html) => {
let text = "hi"

// replace the tags

return html
}

console.log(changeTagByText(html)) 

output excepted:

<h1>title</h1><p>Lorem ipsum dolor quas!</p><p>Lorem ipsum dolor</p><h2>hi</h2><p>hi 123</p><h2>hi</h2><span>Lorem ipsum dolor, sit.</span>