shouldUpdateScroll is not called on the initial page load

[muravitskiy]

Description

I'm using anchor links like /help#faqs, but the page is not scrolled to the specified id on the initial load - shouldUpdateScroll is not called. If the website was loaded - clicking the link works as expected and page scrolls. One possible solution is to add componentDidMount to https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-react-router-scroll/src/ScrollBehaviorContext.js and call this.scrollBehavior.updateScroll but it is not clear what to use for prevRouterProps

Steps to reproduce

add export to your gatsby-browser.js

exports.shouldUpdateScroll = () => {
  console.log('Should update scroll');
}

update the page and check that no message is present

Expected result

shouldUpdateScroll is called and the anchor link scrolls the page

Actual result

shouldUpdateScroll is called only after clicking a link if the app is loaded already

Environment

System:
    OS: macOS 10.14.6
    CPU: (4) x64 Intel(R) Core(TM) i5-7360U CPU @ 2.30GHz
    Shell: 3.2.57 - /bin/bash
  Binaries:
    Node: 12.12.0 - /usr/local/bin/node
    Yarn: 1.19.1 - /usr/local/bin/yarn
    npm: 6.11.3 - /usr/local/bin/npm
  Languages:
    Python: 2.7.16 - /usr/bin/python
  Browsers:
    Chrome: 81.0.4044.129
    Firefox: 70.0.1
    Safari: 13.1
  npmPackages:
    gatsby: ^2.15.28 => 2.20.10
    gatsby-image: ^2.2.21 => 2.3.1
    gatsby-plugin-catch-links: ^2.1.12 => 2.2.1
    gatsby-plugin-eslint: ^2.0.1 => 2.0.8
    gatsby-plugin-favicon: ^3.1.0 => 3.1.6
    gatsby-plugin-mdx: ^1.1.4 => 1.1.4
    gatsby-plugin-react-helmet: ^3.1.10 => 3.2.1
    gatsby-plugin-react-svg: ^3.0.0 => 3.0.0
    gatsby-plugin-resolve-src: ^2.0.0-beta.1 => 2.0.0
    gatsby-plugin-robots-txt: ^1.5.0 => 1.5.0
    gatsby-plugin-sass: ^2.1.17 => 2.2.1
    gatsby-plugin-sharp: ^2.5.3 => 2.5.3
    gatsby-plugin-sitemap: ^2.2.27 => 2.3.1
    gatsby-remark-copy-linked-files: ^2.2.3 => 2.2.3
    gatsby-remark-images: ^3.2.1 => 3.2.1
    gatsby-source-filesystem: ^2.2.2 => 2.2.2
    gatsby-transformer-remark: ^2.6.26 => 2.7.1
    gatsby-transformer-sharp: ^2.4.3 => 2.4.3
    gatsby-transformer-yaml: ^2.3.1 => 2.3.1
    gatsby-transformer-yaml-full: ^0.2.0 => 0.2.0
    gatsby-yaml-full-file: ^0.2.0 => 0.2.0
    gatsby-yaml-full-markdown: ^0.2.1 => 0.2.1
  npmGlobalPackages:
    gatsby-cli: 2.8.2

[blainekasten]

Fixed in latest!

[HashemKhalifa]

@blainekasten you saved my day, thanks!