Add new lint to disallow use of confusing isNaN (#4999)

.eslintrc

@@ -15,6 +15,13 @@
     "rules": {
       "@typescript-eslint/no-floating-promises": "error",
       "@typescript-eslint/no-misused-promises": "error",
+      "no-restricted-globals": [
+        "error",
+        {
+          "name": "isNaN",
+          "message": "Use Number.isNaN() instead."
+        }
+      ],
       "semi": [
         "error",
         "never"

packages/codemirror-lsp-client/src/client/codec/demuxer.ts

@@ -42,7 +42,7 @@ export default class StreamDemuxer extends Queue<Uint8Array> {
           // try to parse the content-length from the headers
           const length = parseInt(match[1])
 
-          if (isNaN(length))
+          if (Number.isNaN(length))
             return Promise.reject(new Error('invalid content length'))
 
           // slice the headers since we now have the content length

src/lib/utils.ts

@@ -345,7 +345,7 @@ export function onDragNumberCalculation(text: string, e: MouseEvent) {
   )
   const newVal = roundOff(addition, precision)
 
-  if (isNaN(newVal)) {
+  if (Number.isNaN(newVal)) {
     return
   }