Check if source contains a valid IFRAME code

This is the regular expression I use to be sure if an arbitrary mark-up is an actual valid iframe code or not:

let someMarkupCode = '...'

let re = /<iframe [.\s\S]*<\/\s*?iframe>/gim
let check = someMarkupCode.match(re)

if (check && check.length > 0) {
  console.log('is an IFRAME')
} else {
  console.log('is not!')
}

That’s it!