[eslint] ESLint - "window" is not defined. How to allow global variables in package.json

I am assigning a property to the global window object, but when I run eslint, I get this:

"window" is not defined

I see this here in the eslint docs:

the following defines window as a global variable for code that should not trigger the rule being tested:

valid: [
  {
    code: "window.alert()",
    globals: [ "window" ]
  }
]

I've tried adding something like this to the package.json file to have eslint allow "window" as a global variable, but I must be doing something wrong. From the docs it seems like I might need to do something like this in a separate file, but is there a way to define some allowed global variables right in the package.json file?

Add .eslintrc in the project root.

{
  "globals": {
    "document": true,
    "foo": true,
    "window": true
  }
}

There is a builtin environment: browser that includes window.

Example .eslintrc.json:

"env": {
    "browser": true,
    "node": true,
    "jasmine": true
  },

More information: http://eslint.org/docs/user-guide/configuring.html#specifying-environments

Also see the package.json answer by chevin99 below.

Your .eslintrc.json should contain the text below.
This way ESLint knows about your global variables.

{
  "env": {
    "browser": true,
    "node": true
  }                                                                      
}

I'm aware he's not asking for the inline version. But since this question has almost 100k visits and I fell here looking for that, I'll leave it here for the next fellow coder:

Make sure ESLint is not run with the --no-inline-config flag (if this doesn't sound familiar, you're likely good to go). Then, write this in your code file (for clarity and convention, it's written on top of the file but it'll work anywhere):

/* eslint-env browser */

This tells ESLint that your working environment is a browser, so now it knows what things are available in a browser and adapts accordingly.

There are plenty of environments, and you can declare more than one at the same time, for example, in-line:

/* eslint-env browser, node */

If you are almost always using particular environments, it's best to set it in your ESLint's config file and forget about it.

From their docs:

An environment defines global variables that are predefined. The available environments are:

• browser - browser global variables.
• node - Node.js global variables and Node.js scoping.
• commonjs - CommonJS global variables and CommonJS scoping (use this for browser-only code that uses Browserify/WebPack).
• shared-node-browser - Globals common to both Node and Browser.

[...]

Besides environments, you can make it ignore anything you want. If it warns you about using console.log() but you don't want to be warned about it, just inline:

/* eslint-disable no-console */

You can see the list of all rules, including recommended rules to have for best coding practices.

If you are using Angular you can get it off with:

"env": {
    "browser": true,
    "node": true
},
"rules" : {
    "angular/window-service": 0
 }