Assuming that we don't have nothing related to JavaScript installed or configured.
Based on https://www.rockyourcode.com/vim-and-svelte-js
wget -qO- https://raw.githubusercontent.com/nvm-sh/nvm/v0.34.0/install.sh | bash
nvm install node
npm install -g npx eslint prettier eslint-config-prettier eslint-plugin-prettier svelte eslint-plugin-svelte3
npx degit sveltejs/template svelte-test
cd svelte-test/
eslint --init
vim .eslintrc.js
Fix it according to https://github.com/sveltejs/eslint-plugin-svelte3/blob/master/README.md#installation
Add plugins for linting, highliting and prettifing to vimrc this example using Plug
Plug 'pangloss/vim-javascript'
Plug 'maxmellon/vim-jsx-pretty'
Plug 'w0rp/ale'
Plug 'burner/vim-svelte'
Congigure ALE to use check html and css before javascript
let g:ale_linter_aliases = {'svelte': ['css', 'javascript']}
let g:ale_linters = {'svelte': ['stylelint', 'eslint']}