We've gathered "the essentials" of ways you can install your Alli snippet on your Typo3 website. Depending on the Typo3 version (and template used), here are the options you can try at the backend of your website.
HeaderData TypoScript
IncludeJS TypoScript
Extbase AdditionalHeaderData
Extbase AssetCollector
Rendering Order of Assets in TYPO3From v10.3, CSS and JavaScript registered with the AssetCollector will be rendered after their PageRenderer counterparts. The order is
<head>
page.includeJSLibs.forceOnTop
page.includeJSLibs
page.includeJS.forceOnTop
page.includeJS
AssetCollector::addJavaScript() with ‘priority’
page.jsInline
AssetCollector::addInlineJavaScript() with ‘priority’
</head>
page.includeJSFooterlibs.forceOnTop
page.includeJSFooterlibs
page.includeJSFooter.forceOnTop
page.includeJSFooter
AssetCollector::addJavaScript()
page.jsFooterInline
AssetCollector::addInlineJavaScript()
Source link: https://t3terminal.com/blog/add-css-js-typo3/
With either of the above-listed options open on your web browser, you would want to open a new window or tab and login to your Alli dashboard to grab a copy of the JavaScript snippet.
...And then just paste it for the appropriate option! That's it. Alli is now installed. =)