Where should I place my Vaadin 10+ static files?

In Vaadin 10-14, where should I place my static files, such as CSS, JavaScript, and Polymer templates? How about static files such as images?

Also, how do I import these files in Vaadin? Is there a difference between Vaadin 14 with npm and Vaadin 10-13 with bower?

All paths are relative to the project root, e.g. where the pom.xml file is located in a Maven project.

JavaScript imported using @JsModule uses strict mode. Among other things, this means that global variables must be defined on the window object, window.x = ..., instead of just x = ....

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Vaadin 14 with npm

Non-Spring Boot projects (war packaging)

• CSS files
  • @CssImport("./my-styles/styles.css")^[1]
  • /frontend/my-styles/styles.css
• JavaScript and Polymer templates
  • @JsModule("./src/my-script.js")^[1]
  • /frontend/src/my-script.js
• Static files, e.g. images
  • new Image("img/flower.jpg", "A flower")
  • /src/main/webapp/img/flower.jpg

Spring Boot projects (jar packaging)

• CSS files
  • @CssImport("./my-styles/styles.css")^[1]
  • /frontend/my-styles/styles.css
• JavaScript and Polymer templates
  • @JsModule("./src/my-script.js")^[1]
  • /frontend/src/my-script.js
• Static files, e.g. images
  • new Image("img/flower.jpg", "A flower")
  • /src/main/resources/META-INF/resources/img/flower.jpg

Add-ons (jar packaging)

• CSS files
  • @CssImport("./my-styles/styles.css")^[1]
  • /src/main/resources/META-INF/resources/frontend/my-styles/styles.css
• JavaScript and Polymer templates
  • @JsModule("./src/my-script.js")^[1]
  • /src/main/resources/META-INF/resources/frontend/src/my-script.js
• Static files, e.g. images
  • new Image("img/flower.jpg", "A flower")
  • /src/main/resources/META-INF/resources/img/flower.jpg

---

Vaadin 10-13, Vaadin 14 in compatibility mode

Non-Spring Boot projects (war packaging)

• CSS files
  • @StyleSheet("css/styles.css")^[2]
  • /src/main/webapp/frontend/css/styles.css
• Polymer templates, custom-style and dom-module styles
  • @HtmlImport("src/template.html")
  • /src/main/webapp/frontend/src/template.html
• JavaScript
  • @JavaScript("js/script.js")^[3]
  • /src/main/webapp/frontend/js/script.js
• Static files, e.g. images
  • new Image("img/flower.jpg", "A flower")
  • /src/main/webapp/img/flower.jpg

Spring Boot projects and add-ons (jar packaging)

• CSS files
  • @StyleSheet("css/styles.css")^[2]
  • /src/main/resources/META-INF/resources/frontend/css/styles.css
• Polymer templates, custom-style and dom-module styles
  • @HtmlImport("src/template.html")
  • /src/main/resources/META-INF/resources/frontend/src/template.html
• JavaScript
  • @JavaScript("js/script.js")^[3]
  • /src/main/resources/META-INF/resources/frontend/js/script.js
• Static files, e.g. images
  • new Image("img/flower.jpg", "A flower")
  • /src/main/resources/META-INF/resources/img/flower.jpg

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Footnotes

^[1] The @JsModule and @CssImport annotations can also be used for importing from an npm package. In this case, the path is defined as @JsModule("@polymer/paper-input") or @CssImport("some-package/style.css"). Paths referring to the local frontend directory should be prefixed with ./

^[2] The @StyleSheet annotation can also be used in Vaadin 14 with npm. The same paths as in V10-V13 can be used, including the context:// protocol @StyleSheet("context://style.css"), which resolves the path relative to the context path of the web application, like other static files. Styles included this way may cause issues with web components.

^[3] The @JavaScript annotation can also be used in Vaadin 14 with npm. The V14 /frontend folder should then be used,.