When including additional JavaScript files in a Lightning web component, a developer should keep in mind twoconsiderations: the files must be ES6 modules and must have names that are unique within the component' s folder and a module can export named functions or variables. The files must be ES6 modules because LWC uses ES6 modules as the standard for modular JavaScript code. The files must have names that are unique within the component's folder because LWC uses the file name as the module identifier and does not allow duplicate identifiers. A module can export named functions or variables because LWC supports named exports, which allow a module to export multiple values with different names. Each additional file does not need a corresponding .js-meta.xml file, as this is only required for the main JavaScript file of the component.
Additional JavaScript files should not be minified before deployment, as this is not necessary or recommended for LWC. Salesforce References: [Lightning Web Components Developer Guide: Include JavaScript Files], [Lightning Web Components Developer Guide: ES6 Modules]