Location Data from Props
What is location data
Sometimes it can be helpful to know exactly what your app’s browser URL is at any given stage. Because Gatsby uses @reach/router for client-side routing, the location prop is passed to any page component and represents where the app is currently, where you’d like it to go, and other helpful information. The location object is never mutated but reach@router makes it helpful to determine when navigation happens. Here is a sample props.location:
Note that you have to parse the search field (the query string) into individual keys and values yourself.
HashHistory
Using hash in JavaScript is one way to update the browser URL and the DOM without having the browser do a full HTML page reload. HashHistory in @reach/router is used to track browser history with JavaScript when using hashrouter instead of browserrouter which uses the newer HTML5 history API.
Getting the absolute URL of a page
The location object’s properties generally do not include the domain of your site, since Gatsby doesn’t know where you will deploy it.
Running client side is the exception to this rule. In this case, all the information your browser exposes as window.location is available. This includes href for the absolute URL of the page, including the domain.
Sometimes you need the absolute URL of the current page (including the host name) while using server-side rendering. For example, you may want to add a canonical URL to the page header.
In this case, you would first need to add configuration that describes where your site is deployed. You can add this as a siteURL property on siteMetadata in gatsby-config.js.
Once you have added siteURL, you can form the absolute URL of the current page by retrieving siteURL and concatenating it with the current path from location. Note that the path starts with a slash; siteURL must therefore not end in one.
Use cases
Through client-side routing in Gatsby you can provide a location object instead of strings, which are helpful in a number of situations:
- Providing state to linked components
- Client-only routes
- Fetching data
- Animation transitions
Example of providing state to a link component
Then from the receiving component you can conditionally render markup based on the location state.