Is it necesary to have already installed node.js to install ESlint?

npm is mostly just moving files around for you - if you want to install it without npm, just move the files around yourself.

E.g. go grab the latest release of eslint from github, copy it to your enterprise computer (network/flash drive?) and unpack it. Then call it directly using node path/to/bin/eslint.js.

If you have node.js installed it should work - if not, you'll need to use a similar approach to install that.

To execute it without prefixing the command with node, e.g. just eslint, you would need to install a .cmd wrapper alongside it. npm does this using cmd-shim

If you wanted to run it without having node.js installed, then you would need to package the node.js runtime and eslint together - options for this include pkg and nexe

To get VSCode to run eslint, you would need to setup a custom task runner by adding a tasks.js file to your project - e.g:

{
  // See https://go.microsoft.com/fwlink/?LinkId=733558
  // for the documentation about the tasks.json format
  "version": "2.0.0",
  "tasks": [
    {
      "label": "eslint-fix",
      "type": "shell",
      "command": "path/to/your/packaged/eslint --fix"
    }
  ]
}

Then you can use the Tasks: Run Task command to find and execute it - or setup a shortcut - for more details see the docs https://code.visualstudio.com/docs/editor/tasks#_custom-tasks

I have created a Github repo for creating a tailored Eslint standalone binary here: Eslint-Standalone

This uses node, npm and pkg to build a eslint tool into a binary, such as an exe for win platform. You can then use that exe and copy it into your network at work with restrictions when it comes to npm.