diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 0e9f644a4905f880b5a8d3c8664c895938727e00..8e58931158b1825426c406ccee718e59670cc328 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -12,7 +12,12 @@ stages:
 check_format:
   stage: source_check
   script:
-    - npx prettier -c --ignore-path .gitignore {.,**}/*.{html,js,json,md}
+    - npx prettier --ignore-path .gitignore --check "**/*.{html,js,json,md}"
+
+lint:
+  stage: source_check
+  script:
+    - npx eslint --ignore-path .gitignore "**/*.js"
 
 backend_build:
   stage: build
diff --git a/package-lock.json b/package-lock.json
index 125fe3aa6eb55b2802092cc00c74a932cbbb92d0..7f8bbec2271235511d607ca6d6a7aba99bca072a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -872,6 +872,12 @@
         }
       }
     },
+    "acorn-jsx": {
+      "version": "5.0.2",
+      "resolved": "https://registry.npmjs.org/acorn-jsx/-/acorn-jsx-5.0.2.tgz",
+      "integrity": "sha512-tiNTrP1MP0QrChmD2DdupCr6HWSFeKVw5d/dHTu4Y7rkAkRhU/Dt7dphAfIUyxtHpl/eBVip5uTNSpQJHylpAw==",
+      "dev": true
+    },
     "acorn-walk": {
       "version": "6.2.0",
       "resolved": "https://registry.npmjs.org/acorn-walk/-/acorn-walk-6.2.0.tgz",
@@ -933,6 +939,15 @@
       "integrity": "sha512-Y9J6ZjXtoYh8RnXVCMOU/ttDmk1aBjunq9vO0ta5x85WDQiQfUF9sIPBITdbiiIVcBo03Hi3jMxigBtsddlXRw==",
       "dev": true
     },
+    "argparse": {
+      "version": "1.0.10",
+      "resolved": "https://registry.npmjs.org/argparse/-/argparse-1.0.10.tgz",
+      "integrity": "sha512-o5Roy6tNG4SL/FOkCAN6RzjiakZS25RLYFrcMttJqbdd8BWrnA+fGz57iN5Pb06pvBGvl5gQ0B48dJlslXvoTg==",
+      "dev": true,
+      "requires": {
+        "sprintf-js": "~1.0.2"
+      }
+    },
     "arr-diff": {
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/arr-diff/-/arr-diff-4.0.0.tgz",
@@ -2409,6 +2424,15 @@
         "randombytes": "^2.0.0"
       }
     },
+    "doctrine": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/doctrine/-/doctrine-3.0.0.tgz",
+      "integrity": "sha512-yS+Q5i3hBf7GBkd4KG8a7eBNNWNGLTaEwwYWUijIYM7zrlYDM0BFXHjjPWlWZ1Rg7UaddZeIDmi9jF3HmqiQ2w==",
+      "dev": true,
+      "requires": {
+        "esutils": "^2.0.2"
+      }
+    },
     "domain-browser": {
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/domain-browser/-/domain-browser-1.2.0.tgz",
@@ -2604,6 +2628,175 @@
         "source-map": "~0.6.1"
       }
     },
+    "eslint": {
+      "version": "6.5.1",
+      "resolved": "https://registry.npmjs.org/eslint/-/eslint-6.5.1.tgz",
+      "integrity": "sha512-32h99BoLYStT1iq1v2P9uwpyznQ4M2jRiFB6acitKz52Gqn+vPaMDUTB1bYi1WN4Nquj2w+t+bimYUG83DC55A==",
+      "dev": true,
+      "requires": {
+        "@babel/code-frame": "^7.0.0",
+        "ajv": "^6.10.0",
+        "chalk": "^2.1.0",
+        "cross-spawn": "^6.0.5",
+        "debug": "^4.0.1",
+        "doctrine": "^3.0.0",
+        "eslint-scope": "^5.0.0",
+        "eslint-utils": "^1.4.2",
+        "eslint-visitor-keys": "^1.1.0",
+        "espree": "^6.1.1",
+        "esquery": "^1.0.1",
+        "esutils": "^2.0.2",
+        "file-entry-cache": "^5.0.1",
+        "functional-red-black-tree": "^1.0.1",
+        "glob-parent": "^5.0.0",
+        "globals": "^11.7.0",
+        "ignore": "^4.0.6",
+        "import-fresh": "^3.0.0",
+        "imurmurhash": "^0.1.4",
+        "inquirer": "^6.4.1",
+        "is-glob": "^4.0.0",
+        "js-yaml": "^3.13.1",
+        "json-stable-stringify-without-jsonify": "^1.0.1",
+        "levn": "^0.3.0",
+        "lodash": "^4.17.14",
+        "minimatch": "^3.0.4",
+        "mkdirp": "^0.5.1",
+        "natural-compare": "^1.4.0",
+        "optionator": "^0.8.2",
+        "progress": "^2.0.0",
+        "regexpp": "^2.0.1",
+        "semver": "^6.1.2",
+        "strip-ansi": "^5.2.0",
+        "strip-json-comments": "^3.0.1",
+        "table": "^5.2.3",
+        "text-table": "^0.2.0",
+        "v8-compile-cache": "^2.0.3"
+      },
+      "dependencies": {
+        "ansi-escapes": {
+          "version": "3.2.0",
+          "resolved": "https://registry.npmjs.org/ansi-escapes/-/ansi-escapes-3.2.0.tgz",
+          "integrity": "sha512-cBhpre4ma+U0T1oM5fXg7Dy1Jw7zzwv7lt/GoCpr+hDQJoYnKVPLL4dCvSEFMmQurOQvSrwT7SL/DAlhBI97RQ==",
+          "dev": true
+        },
+        "ansi-regex": {
+          "version": "4.1.0",
+          "resolved": "https://registry.npmjs.org/ansi-regex/-/ansi-regex-4.1.0.tgz",
+          "integrity": "sha512-1apePfXM1UOSqw0o9IiFAovVz9M5S1Dg+4TrDwfMewQ6p/rmMueb7tWZjQ1rx4Loy1ArBggoqGpfqqdI4rondg==",
+          "dev": true
+        },
+        "ansi-styles": {
+          "version": "3.2.1",
+          "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-3.2.1.tgz",
+          "integrity": "sha512-VT0ZI6kZRdTh8YyJw3SMbYm/u+NqfsAxEpWO0Pf9sq8/e94WxxOpPKx9FR1FlyCtOVDNOQ+8ntlqFxiRc+r5qA==",
+          "dev": true,
+          "requires": {
+            "color-convert": "^1.9.0"
+          }
+        },
+        "chalk": {
+          "version": "2.4.2",
+          "resolved": "https://registry.npmjs.org/chalk/-/chalk-2.4.2.tgz",
+          "integrity": "sha512-Mti+f9lpJNcwF4tWV8/OrTTtF1gZi+f8FqlyAdouralcFWFQWF2+NgCHShjkCb+IFBLq9buZwE1xckQU4peSuQ==",
+          "dev": true,
+          "requires": {
+            "ansi-styles": "^3.2.1",
+            "escape-string-regexp": "^1.0.5",
+            "supports-color": "^5.3.0"
+          }
+        },
+        "chardet": {
+          "version": "0.7.0",
+          "resolved": "https://registry.npmjs.org/chardet/-/chardet-0.7.0.tgz",
+          "integrity": "sha512-mT8iDcrh03qDGRRmoA2hmBJnxpllMR+0/0qlzjqZES6NdiWDcZkCNAk4rPFZ9Q85r27unkiNNg8ZOiwZXBHwcA==",
+          "dev": true
+        },
+        "debug": {
+          "version": "4.1.1",
+          "resolved": "https://registry.npmjs.org/debug/-/debug-4.1.1.tgz",
+          "integrity": "sha512-pYAIzeRo8J6KPEaJ0VWOh5Pzkbw/RetuzehGM7QRRX5he4fPHx2rdKMB256ehJCkX+XRQm16eZLqLNS8RSZXZw==",
+          "dev": true,
+          "requires": {
+            "ms": "^2.1.1"
+          }
+        },
+        "eslint-scope": {
+          "version": "5.0.0",
+          "resolved": "https://registry.npmjs.org/eslint-scope/-/eslint-scope-5.0.0.tgz",
+          "integrity": "sha512-oYrhJW7S0bxAFDvWqzvMPRm6pcgcnWc4QnofCAqRTRfQC0JcwenzGglTtsLyIuuWFfkqDG9vz67cnttSd53djw==",
+          "dev": true,
+          "requires": {
+            "esrecurse": "^4.1.0",
+            "estraverse": "^4.1.1"
+          }
+        },
+        "external-editor": {
+          "version": "3.1.0",
+          "resolved": "https://registry.npmjs.org/external-editor/-/external-editor-3.1.0.tgz",
+          "integrity": "sha512-hMQ4CX1p1izmuLYyZqLMO/qGNw10wSv9QDCPfzXfyFrOaCSSoRfqE1Kf1s5an66J5JZC62NewG+mK49jOCtQew==",
+          "dev": true,
+          "requires": {
+            "chardet": "^0.7.0",
+            "iconv-lite": "^0.4.24",
+            "tmp": "^0.0.33"
+          }
+        },
+        "glob-parent": {
+          "version": "5.1.0",
+          "resolved": "https://registry.npmjs.org/glob-parent/-/glob-parent-5.1.0.tgz",
+          "integrity": "sha512-qjtRgnIVmOfnKUE3NJAQEdk+lKrxfw8t5ke7SXtfMTHcjsBfOfWXCQfdb30zfDoZQ2IRSIiidmjtbHZPZ++Ihw==",
+          "dev": true,
+          "requires": {
+            "is-glob": "^4.0.1"
+          }
+        },
+        "inquirer": {
+          "version": "6.5.2",
+          "resolved": "https://registry.npmjs.org/inquirer/-/inquirer-6.5.2.tgz",
+          "integrity": "sha512-cntlB5ghuB0iuO65Ovoi8ogLHiWGs/5yNrtUcKjFhSSiVeAIVpD7koaSU9RM8mpXw5YDi9RdYXGQMaOURB7ycQ==",
+          "dev": true,
+          "requires": {
+            "ansi-escapes": "^3.2.0",
+            "chalk": "^2.4.2",
+            "cli-cursor": "^2.1.0",
+            "cli-width": "^2.0.0",
+            "external-editor": "^3.0.3",
+            "figures": "^2.0.0",
+            "lodash": "^4.17.12",
+            "mute-stream": "0.0.7",
+            "run-async": "^2.2.0",
+            "rxjs": "^6.4.0",
+            "string-width": "^2.1.0",
+            "strip-ansi": "^5.1.0",
+            "through": "^2.3.6"
+          }
+        },
+        "semver": {
+          "version": "6.3.0",
+          "resolved": "https://registry.npmjs.org/semver/-/semver-6.3.0.tgz",
+          "integrity": "sha512-b39TBaTSfV6yBrapU89p5fKekE2m/NwnDocOVruQFS1/veMgdzuPcnOM34M6CwxW8jH/lxEa5rBoDeUwu5HHTw==",
+          "dev": true
+        },
+        "strip-ansi": {
+          "version": "5.2.0",
+          "resolved": "https://registry.npmjs.org/strip-ansi/-/strip-ansi-5.2.0.tgz",
+          "integrity": "sha512-DuRs1gKbBqsMKIZlrffwlug8MHkcnpjs5VPmL1PAh+mA30U0DTotfDZ0d2UUsXpPmPmMMJ6W773MaA3J+lbiWA==",
+          "dev": true,
+          "requires": {
+            "ansi-regex": "^4.1.0"
+          }
+        },
+        "supports-color": {
+          "version": "5.5.0",
+          "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-5.5.0.tgz",
+          "integrity": "sha512-QjVjwdXIt408MIiAqCX4oUKsgU2EqAGzs2Ppkm4aQYbjm+ZEWEcW4SfFNTr4uMNZma0ey4f5lgLrkB0aX0QMow==",
+          "dev": true,
+          "requires": {
+            "has-flag": "^3.0.0"
+          }
+        }
+      }
+    },
     "eslint-scope": {
       "version": "4.0.3",
       "resolved": "https://registry.npmjs.org/eslint-scope/-/eslint-scope-4.0.3.tgz",
@@ -2614,12 +2807,55 @@
         "estraverse": "^4.1.1"
       }
     },
+    "eslint-utils": {
+      "version": "1.4.2",
+      "resolved": "https://registry.npmjs.org/eslint-utils/-/eslint-utils-1.4.2.tgz",
+      "integrity": "sha512-eAZS2sEUMlIeCjBeubdj45dmBHQwPHWyBcT1VSYB7o9x9WRRqKxyUoiXlRjyAwzN7YEzHJlYg0NmzDRWx6GP4Q==",
+      "dev": true,
+      "requires": {
+        "eslint-visitor-keys": "^1.0.0"
+      }
+    },
+    "eslint-visitor-keys": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/eslint-visitor-keys/-/eslint-visitor-keys-1.1.0.tgz",
+      "integrity": "sha512-8y9YjtM1JBJU/A9Kc+SbaOV4y29sSWckBwMHa+FGtVj5gN/sbnKDf6xJUl+8g7FAij9LVaP8C24DUiH/f/2Z9A==",
+      "dev": true
+    },
+    "espree": {
+      "version": "6.1.1",
+      "resolved": "https://registry.npmjs.org/espree/-/espree-6.1.1.tgz",
+      "integrity": "sha512-EYbr8XZUhWbYCqQRW0duU5LxzL5bETN6AjKBGy1302qqzPaCH10QbRg3Wvco79Z8x9WbiE8HYB4e75xl6qUYvQ==",
+      "dev": true,
+      "requires": {
+        "acorn": "^7.0.0",
+        "acorn-jsx": "^5.0.2",
+        "eslint-visitor-keys": "^1.1.0"
+      },
+      "dependencies": {
+        "acorn": {
+          "version": "7.1.0",
+          "resolved": "https://registry.npmjs.org/acorn/-/acorn-7.1.0.tgz",
+          "integrity": "sha512-kL5CuoXA/dgxlBbVrflsflzQ3PAas7RYZB52NOm/6839iVYJgKMJ3cQJD+t2i5+qFa8h3MDpEOJiS64E8JLnSQ==",
+          "dev": true
+        }
+      }
+    },
     "esprima": {
       "version": "3.1.3",
       "resolved": "https://registry.npmjs.org/esprima/-/esprima-3.1.3.tgz",
       "integrity": "sha1-/cpRzuYTOJXjyI1TXOSdv/YqRjM=",
       "dev": true
     },
+    "esquery": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/esquery/-/esquery-1.0.1.tgz",
+      "integrity": "sha512-SmiyZ5zIWH9VM+SRUReLS5Q8a7GxtRdxEBVZpm98rJM7Sb+A9DVCndXfkeFUd3byderg+EbDkfnevfCwynWaNA==",
+      "dev": true,
+      "requires": {
+        "estraverse": "^4.0.0"
+      }
+    },
     "esrecurse": {
       "version": "4.2.1",
       "resolved": "https://registry.npmjs.org/esrecurse/-/esrecurse-4.2.1.tgz",
@@ -2984,6 +3220,15 @@
         "escape-string-regexp": "^1.0.5"
       }
     },
+    "file-entry-cache": {
+      "version": "5.0.1",
+      "resolved": "https://registry.npmjs.org/file-entry-cache/-/file-entry-cache-5.0.1.tgz",
+      "integrity": "sha512-bCg29ictuBaKUwwArK4ouCaqDgLZcysCFLmM/Yn/FDoqndh/9vNuQfXRDvTuXKLxfD/JtZQGKFT8MGcJBK644g==",
+      "dev": true,
+      "requires": {
+        "flat-cache": "^2.0.1"
+      }
+    },
     "fill-range": {
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/fill-range/-/fill-range-4.0.0.tgz",
@@ -3068,6 +3313,34 @@
         "resolve-dir": "^1.0.1"
       }
     },
+    "flat-cache": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/flat-cache/-/flat-cache-2.0.1.tgz",
+      "integrity": "sha512-LoQe6yDuUMDzQAEH8sgmh4Md6oZnc/7PjtwjNFSzveXqSHt6ka9fPBuso7IGf9Rz4uqnSnWiFH2B/zj24a5ReA==",
+      "dev": true,
+      "requires": {
+        "flatted": "^2.0.0",
+        "rimraf": "2.6.3",
+        "write": "1.0.3"
+      },
+      "dependencies": {
+        "rimraf": {
+          "version": "2.6.3",
+          "resolved": "https://registry.npmjs.org/rimraf/-/rimraf-2.6.3.tgz",
+          "integrity": "sha512-mwqeW5XsA2qAejG46gYdENaxXjx9onRNCfn7L0duuP4hCuTIi/QO7PDK07KJfp1d+izWPrzEJDcSqBa0OZQriA==",
+          "dev": true,
+          "requires": {
+            "glob": "^7.1.3"
+          }
+        }
+      }
+    },
+    "flatted": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/flatted/-/flatted-2.0.1.tgz",
+      "integrity": "sha512-a1hQMktqW9Nmqr5aktAux3JMNqaucxGcjtjWnZLHX7yyPCmlSV3M54nGYbqT8K+0GhF3NBgmJCc3ma+WOgX8Jg==",
+      "dev": true
+    },
     "flush-write-stream": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/flush-write-stream/-/flush-write-stream-1.1.1.tgz",
@@ -3710,6 +3983,12 @@
       "integrity": "sha512-yIovAzMX49sF8Yl58fSCWJ5svSLuaibPxXQJFLmBObTuCr0Mf1KiPopGM9NiFjiYBCbfaa2Fh6breQ6ANVTI0A==",
       "dev": true
     },
+    "functional-red-black-tree": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/functional-red-black-tree/-/functional-red-black-tree-1.0.1.tgz",
+      "integrity": "sha1-GwqzvVU7Kg1jmdKcDj6gslIHgyc=",
+      "dev": true
+    },
     "get-caller-file": {
       "version": "2.0.5",
       "resolved": "https://registry.npmjs.org/get-caller-file/-/get-caller-file-2.0.5.tgz",
@@ -4051,6 +4330,30 @@
       "integrity": "sha1-xg7taebY/bazEEofy8ocGS3FtQE=",
       "dev": true
     },
+    "ignore": {
+      "version": "4.0.6",
+      "resolved": "https://registry.npmjs.org/ignore/-/ignore-4.0.6.tgz",
+      "integrity": "sha512-cyFDKrqc/YdcWFniJhzI42+AzS+gNwmUzOSFcRCQYwySuBBBy/KjuxWLZ/FHEH6Moq1NizMOBWyTcv8O4OZIMg==",
+      "dev": true
+    },
+    "import-fresh": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/import-fresh/-/import-fresh-3.1.0.tgz",
+      "integrity": "sha512-PpuksHKGt8rXfWEr9m9EHIpgyyaltBy8+eF6GJM0QCAxMgxCfucMF3mjecK2QsJr0amJW7gTqh5/wht0z2UhEQ==",
+      "dev": true,
+      "requires": {
+        "parent-module": "^1.0.0",
+        "resolve-from": "^4.0.0"
+      },
+      "dependencies": {
+        "resolve-from": {
+          "version": "4.0.0",
+          "resolved": "https://registry.npmjs.org/resolve-from/-/resolve-from-4.0.0.tgz",
+          "integrity": "sha512-pb/MYmXstAkysRFx8piNI1tGFNQIFA3vkE3Gq4EuA1dF6gHp/+vgZqsCGJapvy8N3Q+4o7FwvquPJcnZ7RYy4g==",
+          "dev": true
+        }
+      }
+    },
     "import-local": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/import-local/-/import-local-2.0.0.tgz",
@@ -5324,6 +5627,24 @@
       "integrity": "sha512-RdJUflcE3cUzKiMqQgsCu06FPu9UdIJO0beYbPhHN4k6apgJtifcoCtT9bcxOpYBtpD2kCM6Sbzg4CausW/PKQ==",
       "dev": true
     },
+    "js-yaml": {
+      "version": "3.13.1",
+      "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-3.13.1.tgz",
+      "integrity": "sha512-YfbcO7jXDdyj0DGxYVSlSeQNHbD7XPWvrVWeVUujrQEoZzWJIRrCPoyk6kL6IAjAG2IolMK4T0hNUe0HOUs5Jw==",
+      "dev": true,
+      "requires": {
+        "argparse": "^1.0.7",
+        "esprima": "^4.0.0"
+      },
+      "dependencies": {
+        "esprima": {
+          "version": "4.0.1",
+          "resolved": "https://registry.npmjs.org/esprima/-/esprima-4.0.1.tgz",
+          "integrity": "sha512-eGuFFw7Upda+g4p+QHvnW0RyTX/SVeJBDM/gCtMARO0cLuT2HcEKnTPvhjV6aGeqrCB/sbNop0Kszm0jsaWU4A==",
+          "dev": true
+        }
+      }
+    },
     "jsbn": {
       "version": "0.1.1",
       "resolved": "https://registry.npmjs.org/jsbn/-/jsbn-0.1.1.tgz",
@@ -5399,6 +5720,12 @@
       "integrity": "sha512-xbbCH5dCYU5T8LcEhhuh7HJ88HXuW3qsI3Y0zOZFKfZEHcpWiHU/Jxzk629Brsab/mMiHQti9wMP+845RPe3Vg==",
       "dev": true
     },
+    "json-stable-stringify-without-jsonify": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/json-stable-stringify-without-jsonify/-/json-stable-stringify-without-jsonify-1.0.1.tgz",
+      "integrity": "sha1-nbe1lJatPzz+8wp1FC0tkwrXJlE=",
+      "dev": true
+    },
     "json-stringify-safe": {
       "version": "5.0.1",
       "resolved": "https://registry.npmjs.org/json-stringify-safe/-/json-stringify-safe-5.0.1.tgz",
@@ -6255,6 +6582,15 @@
         "readable-stream": "^2.1.5"
       }
     },
+    "parent-module": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/parent-module/-/parent-module-1.0.1.tgz",
+      "integrity": "sha512-GQ2EWRpQV8/o+Aw8YqtfZZPfNRWZYkbidE9k5rpl/hC3vtHHBfGm2Ifi6qWV+coDGkrUKZAxE3Lot5kcsRlh+g==",
+      "dev": true,
+      "requires": {
+        "callsites": "^3.0.0"
+      }
+    },
     "parse-asn1": {
       "version": "5.1.5",
       "resolved": "https://registry.npmjs.org/parse-asn1/-/parse-asn1-5.1.5.tgz",
@@ -6535,6 +6871,12 @@
       "integrity": "sha512-3ouUOpQhtgrbOa17J7+uxOTpITYWaGP7/AhoR3+A+/1e9skrzelGi/dXzEYyvbxubEF6Wn2ypscTKiKJFFn1ag==",
       "dev": true
     },
+    "progress": {
+      "version": "2.0.3",
+      "resolved": "https://registry.npmjs.org/progress/-/progress-2.0.3.tgz",
+      "integrity": "sha512-7PiHtLll5LdnKIMw100I+8xJXR5gW2QwWYkT6iJva0bXitZKa/XMrSbdmg3r2Xnaidz9Qumd0VPaMrZlF9V9sA==",
+      "dev": true
+    },
     "promise-inflight": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/promise-inflight/-/promise-inflight-1.0.1.tgz",
@@ -6754,6 +7096,12 @@
         "safe-regex": "^1.1.0"
       }
     },
+    "regexpp": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/regexpp/-/regexpp-2.0.1.tgz",
+      "integrity": "sha512-lv0M6+TkDVniA3aD1Eg0DVpfU/booSu7Eev3TDO/mZKHBfVjgCGTV4t4buppESEYDtkArYFOxTJWv6S5C+iaNw==",
+      "dev": true
+    },
     "remove-trailing-separator": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/remove-trailing-separator/-/remove-trailing-separator-1.1.0.tgz",
@@ -6989,6 +7337,15 @@
       "resolved": "https://registry.npmjs.org/rx/-/rx-4.1.0.tgz",
       "integrity": "sha1-pfE/957zt0D+MKqAP7CfmIBdR4I="
     },
+    "rxjs": {
+      "version": "6.5.3",
+      "resolved": "https://registry.npmjs.org/rxjs/-/rxjs-6.5.3.tgz",
+      "integrity": "sha512-wuYsAYYFdWTAnAaPoKGNhfpWwKZbJW+HgAJ+mImp+Epl7BG8oNWBCTyRM8gba9k4lk8BgWdoYm21Mo/RYhhbgA==",
+      "dev": true,
+      "requires": {
+        "tslib": "^1.9.0"
+      }
+    },
     "safe-buffer": {
       "version": "5.1.2",
       "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.1.2.tgz",
@@ -7200,6 +7557,28 @@
       "integrity": "sha512-ZYKh3Wh2z1PpEXWr0MpSBZ0V6mZHAQfYevttO11c51CaWjGTaadiKZ+wVt1PbMlDV5qhMFslpZCemhwOK7C89A==",
       "dev": true
     },
+    "slice-ansi": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/slice-ansi/-/slice-ansi-2.1.0.tgz",
+      "integrity": "sha512-Qu+VC3EwYLldKa1fCxuuvULvSJOKEgk9pi8dZeCVK7TqBfUNTH4sFkk4joj8afVSfAYgJoSOetjx9QWOJ5mYoQ==",
+      "dev": true,
+      "requires": {
+        "ansi-styles": "^3.2.0",
+        "astral-regex": "^1.0.0",
+        "is-fullwidth-code-point": "^2.0.0"
+      },
+      "dependencies": {
+        "ansi-styles": {
+          "version": "3.2.1",
+          "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-3.2.1.tgz",
+          "integrity": "sha512-VT0ZI6kZRdTh8YyJw3SMbYm/u+NqfsAxEpWO0Pf9sq8/e94WxxOpPKx9FR1FlyCtOVDNOQ+8ntlqFxiRc+r5qA==",
+          "dev": true,
+          "requires": {
+            "color-convert": "^1.9.0"
+          }
+        }
+      }
+    },
     "snapdragon": {
       "version": "0.8.2",
       "resolved": "https://registry.npmjs.org/snapdragon/-/snapdragon-0.8.2.tgz",
@@ -7410,6 +7789,12 @@
         "extend-shallow": "^3.0.0"
       }
     },
+    "sprintf-js": {
+      "version": "1.0.3",
+      "resolved": "https://registry.npmjs.org/sprintf-js/-/sprintf-js-1.0.3.tgz",
+      "integrity": "sha1-BOaSb2YolTVPPdAVIDYzuFcpfiw=",
+      "dev": true
+    },
     "sshpk": {
       "version": "1.16.1",
       "resolved": "https://registry.npmjs.org/sshpk/-/sshpk-1.16.1.tgz",
@@ -7613,6 +7998,12 @@
       "integrity": "sha1-u0P/VZim6wXYm1n80SnJgzE2Br8=",
       "dev": true
     },
+    "strip-json-comments": {
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/strip-json-comments/-/strip-json-comments-3.0.1.tgz",
+      "integrity": "sha512-VTyMAUfdm047mwKl+u79WIdrZxtFtn+nBxHeb844XBQ9uMNTuTHdx2hc5RiAJYqwTj3wc/xe5HLSdJSkJ+WfZw==",
+      "dev": true
+    },
     "supports-color": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-2.0.0.tgz",
@@ -7624,6 +8015,46 @@
       "integrity": "sha512-9QNk5KwDF+Bvz+PyObkmSYjI5ksVUYtjW7AU22r2NKcfLJcXp96hkDWU3+XndOsUb+AQ9QhfzfCT2O+CNWT5Tw==",
       "dev": true
     },
+    "table": {
+      "version": "5.4.6",
+      "resolved": "https://registry.npmjs.org/table/-/table-5.4.6.tgz",
+      "integrity": "sha512-wmEc8m4fjnob4gt5riFRtTu/6+4rSe12TpAELNSqHMfF3IqnA+CH37USM6/YR3qRZv7e56kAEAtd6nKZaxe0Ug==",
+      "dev": true,
+      "requires": {
+        "ajv": "^6.10.2",
+        "lodash": "^4.17.14",
+        "slice-ansi": "^2.1.0",
+        "string-width": "^3.0.0"
+      },
+      "dependencies": {
+        "ansi-regex": {
+          "version": "4.1.0",
+          "resolved": "https://registry.npmjs.org/ansi-regex/-/ansi-regex-4.1.0.tgz",
+          "integrity": "sha512-1apePfXM1UOSqw0o9IiFAovVz9M5S1Dg+4TrDwfMewQ6p/rmMueb7tWZjQ1rx4Loy1ArBggoqGpfqqdI4rondg==",
+          "dev": true
+        },
+        "string-width": {
+          "version": "3.1.0",
+          "resolved": "https://registry.npmjs.org/string-width/-/string-width-3.1.0.tgz",
+          "integrity": "sha512-vafcv6KjVZKSgz06oM/H6GDBrAtz8vdhQakGjFIvNrHA6y3HCF1CInLy+QLq8dTJPQ1b+KDUqDFctkdRW44e1w==",
+          "dev": true,
+          "requires": {
+            "emoji-regex": "^7.0.1",
+            "is-fullwidth-code-point": "^2.0.0",
+            "strip-ansi": "^5.1.0"
+          }
+        },
+        "strip-ansi": {
+          "version": "5.2.0",
+          "resolved": "https://registry.npmjs.org/strip-ansi/-/strip-ansi-5.2.0.tgz",
+          "integrity": "sha512-DuRs1gKbBqsMKIZlrffwlug8MHkcnpjs5VPmL1PAh+mA30U0DTotfDZ0d2UUsXpPmPmMMJ6W773MaA3J+lbiWA==",
+          "dev": true,
+          "requires": {
+            "ansi-regex": "^4.1.0"
+          }
+        }
+      }
+    },
     "tapable": {
       "version": "1.1.3",
       "resolved": "https://registry.npmjs.org/tapable/-/tapable-1.1.3.tgz",
@@ -7670,6 +8101,12 @@
         "require-main-filename": "^2.0.0"
       }
     },
+    "text-table": {
+      "version": "0.2.0",
+      "resolved": "https://registry.npmjs.org/text-table/-/text-table-0.2.0.tgz",
+      "integrity": "sha1-f17oI66AUgfACvLfSoTsP8+lcLQ=",
+      "dev": true
+    },
     "throat": {
       "version": "4.1.0",
       "resolved": "https://registry.npmjs.org/throat/-/throat-4.1.0.tgz",
@@ -8388,6 +8825,15 @@
       "integrity": "sha1-tSQ9jz7BqjXxNkYFvA0QNuMKtp8=",
       "dev": true
     },
+    "write": {
+      "version": "1.0.3",
+      "resolved": "https://registry.npmjs.org/write/-/write-1.0.3.tgz",
+      "integrity": "sha512-/lg70HAjtkUgWPVZhZcm+T4hkL8Zbtp1nFNOn3lRrxnlv50SRBv7cR7RqR+GMsd3hUXy9hWBo4CHTbFTcOYwig==",
+      "dev": true,
+      "requires": {
+        "mkdirp": "^0.5.1"
+      }
+    },
     "write-file-atomic": {
       "version": "2.4.1",
       "resolved": "https://registry.npmjs.org/write-file-atomic/-/write-file-atomic-2.4.1.tgz",
diff --git a/package.json b/package.json
index 026a065bec7a6ce6587bbfb7ae1b3b705183246c..594bd9031621e171210604e9a9862a129ff29dbe 100644
--- a/package.json
+++ b/package.json
@@ -27,6 +27,7 @@
     "yjs": "^12.3.3"
   },
   "devDependencies": {
+    "eslint": "^6.5.1",
     "jest": "^24.9.0",
     "prettier": "^1.18.2",
     "webpack": "^4.41.0",
diff --git a/public/service-worker.js b/public/service-worker.js
index 424f928f80eda954a8e8d71a28c2543dfc9e23c2..7e1bb74fe0ff1849c7d5474edbf8fd04a55b4d8c 100644
--- a/public/service-worker.js
+++ b/public/service-worker.js
@@ -19,14 +19,14 @@ const normalizeUrl = (url) => {
   return url_.href
 }
 
-self.addEventListener("install", async (event) => {
+self.addEventListener("install", async () => {
   const cache = await caches.open(CACHE_NAME)
   const additions = cache.addAll(FILES_TO_CACHE)
   await additions
   console.info(`Files cached: [\n  ${FILES_TO_CACHE.join(`,\n  `)}\n]`)
 })
 
-self.addEventListener("activate", async (event) => {
+self.addEventListener("activate", async () => {
   const oldCacheKeys = (await caches.keys()).filter((key) => key != CACHE_NAME)
   oldCacheKeys.forEach((key) => caches.delete(key))
 })
@@ -42,18 +42,7 @@ self.addEventListener("fetch", (event) => {
         return response
       })
       .catch(() => caches.match(normalizedUrl))
-      .catch((e) => null)
+      .catch(() => null)
   }
-  event.respondWith(
-    fetch(event.request)
-      .then(async (response) => {
-        if (FILES_TO_CACHE.includes(new URL(normalizedUrl).pathname)) {
-          const cache = await caches.open(CACHE_NAME)
-          await cache.put(normalizedUrl, response.clone())
-        }
-        return response
-      })
-      .catch(() => caches.match(normalizedUrl))
-      .catch((e) => null),
-  )
+  event.respondWith(response)
 })