Checks reference
You can run the following checks as part of Theme Check. Each check identifies a specific error or a place in your code where a best practice is not being followed.
To learn more about the check and its options, click on the name of the check.
Liquid file checks
Anchor link to section titled "Liquid file checks"These checks analyze the style and validity of Liquid code. Some of these checks support auto-correction using the --auto-correct flag.
| Check | Severity | Purpose | Auto-correction |
|---|---|---|---|
| AppBlockValidTags | Error | Identifies forbidden Liquid tags in theme app extension app block and app embed block code. | |
| AssetPreload | Warning | Encourages preloading of assets using Liquid filters, rather than HTML attributes. | |
| AssetSizeAppBlockCSS | Error | Prevents theme app extensions from using CSS files larger than the configured threshold. | |
| AssetSizeAppBlockJavascript | Error | Prevents theme app extensions from using JavaScript files and external scripts with a compressed size larger than the configured threshold. | |
| AssetSizeCSS | Error | Prevents themes from using CSS files larger than the configured threshold. | |
| AssetSizeJavaScript | Error | Prevents using theme JavaScript files and external scripts with a compressed size greater than the configured threshold. | |
| CdnPreconnect | Warning | This check is aimed at signaling the redundant preconnect to Shopify's CDN. | |
| ContentForHeaderModification | Error | Identifies code that tries to parse content_for_header . |
|
| DeprecateBgsizes | Warning | Discourages use of the bgset extension instead of the image-set attribute for loading background images. | |
| DeprecateLazysizes | Warning | Discourages use of the lazysizes library for lazy loading images, iframes, and scripts. | |
| DeprecatedFilter | Warning | Discourages using deprecated filters in themes. | Yes |
| DeprecatedTag | Error | Discourages using deprecated tags in themes. | |
| ImgWidthAndHeight | Error | Enforces setting the width and height attributes on img tags. |
|
| LiquidHTMLSyntaxError | Error | Identifies Liquid and HTML syntax errors. | |
| MissingAsset | Error | Makes sure that all asset files referenced by the asset_url filter exist. |
|
| MissingTemplate | Warning |
Identifies when a resource is referenced using a render , section , or
include tag, but doesn't exist.
|
Yes |
| PaginationSize | Warning | Ensures that objects are paginated with performant sizes so too many objects are not loaded at once. | |
| ParserBlockingJavaScript | Error | Identifies script tags that don't have defer or async attributes, avoiding parser-blocking JavaScript. | |
| RemoteAsset | Warning | Discourages use of third party domains for hosting assets. | |
| RequiredLayoutThemeObject | Error |
Makes sure that the theme.liquid layout file contains the required
{{ content_for_header }} and {{ content_for_layout }} objects.
|
Yes |
| TranslationKeyExists | Error | Identifies references to translations that don't exist. | |
| UnclosedHTMLElement | Error | Identifies instances of unclosed HTML elements in branching code. | |
| UndefinedObject | Error | Identifies references to undefined Liquid objects. | |
| UnknownFilter | Error | Identifies references to unknown Liquid filters. | |
| UnusedAssign | Warning | Identifies variable definitions that aren't used. | |
| ValidSchema | Warning | Identifies invalid JSON in {% schema %} tags. |
JSON file checks
Anchor link to section titled "JSON file checks"These checks analyze the syntax, content and structure of JSON files.
| Check | Severity | Purpose | Auto-correction |
|---|---|---|---|
| JSONSyntaxError | Error | Identifies invalid JSON files in themes. | |
| MatchingTranslations | Warning | Identifies missing or additional translations in locale files. | Yes |
| ValidHTMLTranslation | Warning | Identifies invalid HTML inside translations. |