added eslint

.eslintrc.cjs

@@ -0,0 +1,24 @@
+module.exports = {
+  root: true,
+  parser: '@typescript-eslint/parser',
+  extends: [
+    'eslint:recommended',
+    'plugin:@typescript-eslint/recommended',
+    'prettier'
+  ],
+  plugins: ['svelte3', '@typescript-eslint'],
+  ignorePatterns: ['*.cjs'],
+  overrides: [{ files: ['*.svelte'], processor: 'svelte3/svelte3' }],
+  settings: {
+    'svelte3/typescript': () => require('typescript')
+  },
+  parserOptions: {
+    sourceType: 'module',
+    ecmaVersion: 2020
+  },
+  env: {
+    browser: true,
+    es2017: true,
+    node: true
+  }
+};