const test = document.createElement('div')

test.innerHTML = '<div>foo bar</div>'

document.body.append(...test.childNodes)

const test = document.createRange().createContextualFragment('<div>foo bar</div>')

document.body.append(test)

const test1 = document.createElement('div')

const test2 = document.createRange().createContextualFragment('<div>foo bar</div>')

​

test1.append(test2)

​

document.body.append(...test1.childNodes)