Adds eslint configuration. (related to #13)

.eslintrc.js

@@ -0,0 +1,64 @@
+function err(...args) {
+    return ["error", ...args];
+}
+
+module.exports = {
+    env: {
+        browser: true,
+        es2021: true,
+        node: true
+    },
+    overrides: [
+    ],
+    parser: "@typescript-eslint/parser",
+    parserOptions: {
+        ecmaVersion: 'latest',
+        sourceType: 'module',
+        project: ["./tsconfig.json"]
+    },
+    plugins: ['@typescript-eslint'],
+    rules: {
+        "indent": err(4),
+        "func-names": err("never"),
+        "consistent-this": err("self"),
+        "default-case-last": err(),
+        "default-param-last": err(),
+        "eqeqeq": err("always", {"null": "ignore"}),
+        "no-delete-var": err(),
+        "no-eval": err(),
+        "no-implied-eval": err(),
+        "no-lone-blocks": err(),
+        "no-lonely-if": err(),
+        "no-return-await": err(),
+        "no-var": err(),
+        "prefer-destructuring": err({"object": true}),
+        "prefer-const": err(),
+        "prefer-arrow-callback": err(),
+        "prefer-rest-params": err(),
+        "prefer-spread": err(),
+        "prefer-template": err(),
+        "require-await": err(),
+        "require-yield": err(),
+        "spaced-comment": err("always"),
+        "comma-dangle": err("always-multiline"),
+        "comma-style": err("last"),
+        "comma-spacing": err(),
+        "eol-last": err("always"),
+        "dot-location": err("property"),
+        "brace-style": err(),
+        "function-paren-newline": err("consistent"),
+        "function-call-argument-newline": err("consistent"),
+        "block-scoped-var": err(),
+        "consistent-return": err(),
+        "no-async-promise-executor": err(),
+        "no-promise-executor-return": err(),
+        "semi": err("always"),
+        "semi-style": err(),
+        "space-unary-ops": err(),
+        "space-infix-ops": err(),
+        "space-before-blocks": err(),
+        "operator-linebreak": err("before"),
+        "@typescript-eslint/no-misused-promises": err(),
+        "@typescript-eslint/no-floating-promises": err(),
+    }
+}