How to get the last time a Gatsby site was built

If your Gatsby site pulls in data at build time, it can be helpful to show visitors when the site was last built.

This component relies on a GraphQL query to fetch the build time, and then formats it using a lightweight package called tiny-relative-date.

Here is an abbreviated component using it (without styling):

import React from "react"
import { useStaticQuery, graphql } from "gatsby"
import relativeDate from "tiny-relative-date"

export default () => {
  const query = useStaticQuery(graphql`
    query {
      site {
        buildTime
      }
    }
  `)

  const buildTime = new Date(query.site.buildTime)
  const buildTimeRelative = relativeDate(buildTime)

  return (
    <p>This site (benborgers.com) was last built {buildTimeRelative}.</p>
  )
}