JSFiddle - React, Tailwind, and code Playground
HTML
<pre id="result"></pre>
Babel + JSX
const ADDON_REG_EXP = /^addon([\d]+)$/
const metafields = [
{ key: 'addon1' },
{ key: 'foo' },
{ key: 'addon5' },
{ key: 'addon2' }
]
const filtered = metafields.filter(m => ADDON_REG_EXP.exec(m.key))
console.log('filtered', filtered)