sanitize-wysiwyg-paste.js

import sanitizeHTML from 'sanitize-html'

const wysiwygSel = '.wysiwyg'
const allowedTags = [
    'b',
    'i',
    'u',
    'br',
]

function pasteEventHTML(e) {
    const html = e.clipboardData.getData("text/html")
    const sanitizedHTML = html && sanitizeHTML(html, {
        allowedTags,
    })
    return sanitizedHTML || e.clipboardData.getData("text/plain")
}

document.addEventListener('paste', function (e) {
    if (!(e.target && e.target.closest(wysiwygSel))) {
        // only overwrite pastes when pasting into a wysiwyg editor
        return
    }
    e.preventDefault()
    document.execCommand("insertHTML", false, pasteEventHTML(e))
});