PostHTML plugin to insert content after HTML tag.
npm install posthtml-insert --save
const posthtml = require('posthtml')
const insert = require('posthtml-insert')
posthtml([insert({ selector: 'body', content: '<div>test</div>' })])
.process('<body></body>')
.then(({ html }) => {
console.log(html)
// => '<body><div>test</div></body>'
})