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remark42/site/src/docs/manuals/integration-with-gatsby/index.md
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# Using Remark42 in Gatsby projects | |
## Sample Comments.js React component: | |
```js | |
import * as React from "react" | |
// This function will insert the usual <script> tag of | |
// Remark42 into the specified DOM location (parentElement) | |
const insertScript = (id, parentElement) => { | |
const script = window.document.createElement("script") | |
script.type = "text/javascript" | |
script.async = true | |
script.id = id | |
/* For Gatsby it's important to manually provide the URL | |
and make sure it does not contain a trailing slash ("/"). | |
Because otherwise the comments for paths with/without | |
the trailing slash are stored separately in the BoltDB database. | |
When following a Gatsby Link a page is loaded without the trailing slash, | |
but when refreshing the page (F5) it is loaded with the trailing slash. | |
So essentially every URL can become duplicated in the DB and you may not see | |
your comments from the inverse URL at your present URL. | |
Making sure url is provided without the trailing slash | |
in the remark42 config solves this. */ | |
let url = window.location.origin + window.location.pathname | |
if(url.endsWith("/")) { | |
url = url.slice(0, -1) | |
} | |
// Now the actual config and script-fetching function: | |
script.innerHTML = ` | |
var remark_config = { | |
host: "https://remark42.example.com", | |
site_id: "example-name", | |
url: "${url}", | |
theme: "dark", | |
components: ["embed"], | |
}; | |
!function(e,n){for(var o=0;o<e.length;o++){var r=n.createElement("script"),c=".js",d=n.head||n.body;"noModule"in r?(r.type="module",c=".mjs"):r.async=!0,r.defer=!0,r.src=remark_config.host+"/web/"+e[o]+c,d.appendChild(r)}}(remark_config.components||["embed"],document);` | |
parentElement.appendChild(script) | |
} | |
/* This function removes the previously added script from the DOM. | |
Might be necessary when page transitions happen, to make sure a new instance | |
is created, pointing to the current URL. Although this might actually | |
not be necessary, please do your own testing.*/ | |
const removeScript = (id, parentElement) => { | |
const script = window.document.getElementById(id) | |
if (script) { | |
parentElement.removeChild(script) | |
} | |
} | |
// This function will be provided to useEffect and will insert the script | |
// when the component is mounted and remove it when it unmounts | |
const manageScript = () => { | |
if (!window) { | |
return | |
} | |
const document = window.document | |
if (document.getElementById("remark42")) { | |
insertScript("comments-script", document.body) | |
} | |
return () => removeScript("comments-script", document.body) | |
} | |
/* Another function for another useEffect - this is the most crucial part for | |
Gatsby compatibility. It will ensure that each page loads its own appropriate | |
comments, and that comments will be properly loaded */ | |
const recreateRemark42Instance = () => { | |
if (!window) { | |
return | |
} | |
const remark42 = window.REMARK42 | |
if (remark42) { | |
remark42.destroy() | |
remark42.createInstance(window.remark_config) | |
} | |
} | |
// The location prop is {props.location.pathname} from the parent component. | |
// I.e. invoke the component like this in the parent: <Comments location={props.location.pathname} /> | |
const Comments = ({ location }) => { | |
// Insert the two useEffect hooks. Maybe you can combine them into one? Feel free if you want to. | |
React.useEffect(manageScript, [location]) | |
React.useEffect(recreateRemark42Instance, [location]) | |
return ( | |
<> | |
<h2>Comments</h2> | |
{ /* This div is the target for actual comments insertion */ } | |
<div id="remark42"></div> | |
</> | |
) | |
} | |
export default Comments | |
``` |