Write a regular expression that inserts <h1>Hello</h1> immediately after the <body> tag. The tag may have attributes. You only have to come up with the regular expression. The replace function is already done (see the Tests tab).
const REGEXP = /your regular expression/
let str = "\<html><body style="height: 200px"> ... </body></html>"
str = str.replace(REGEXP, `<h1>Hello</h1>`)
console.log(str) ➞ <html> <body style="height: 200px"><h1>Hello</h1> ... </body> </html>