LRUCache is both a namespace and a class! about node-lru-cache

[isaacs]

What build issues does it cause? Please provide reproduction, showing expectation and actual behavior.

[JimmyBjorklund]

We are using "coap": "^1.3.0", and when building it seams to get confused about the namespace and class. It should work just fine but for some reason it takes the namespace instead of the class.
Thay do this in there code https://github.com/coapjs/node-coap/blob/master/lib/server.ts

class CoapLRUCache<K extends {}, V extends {}> extends LRUCache<K, V> {
pruneTimer: NodeJS.Timeout
}

node_modules/coap/dist/lib/server.d.ts:11:10 - error TS2617: 'LRUCache' can only be imported by using 'import LRUCache = require("lru-cache")' or by turning on the 'esModuleInterop' flag and using a default import.

11 import { LRUCache } from 'lru-cache';

[isaacs]

Give me some code and a command to run so that I can see it happening. LRUCache seems to build just fine in every situation I've used it, so there's something particular to either your setup or theirs, but if I can't reproduce it, I cannot help you, sorry.

[JimmyBjorklund]

I created a smal sample, the first error is easy to get around and thats just to add { } aroung 3 import BufferListStream from 'bl';
But the last one seams to get the compiler to go bananas, npm run start works but npm run build do not. Only thing i can think of is that its to do with the namespace and class name.
https://github.com/JimmyBjorklund/t-coap

[isaacs]

That is not the problem.

node_modules/coap/dist/lib/server.d.ts:11:8 - error TS1259: Module '"/Users/isaacs/dev/isaacs/lru-cache/t-coap/node_modules/@types/lru-cache/index"' can only be default-imported using the 'esModuleInterop' flag

11 import LRUCache from 'lru-cache';
          ~~~~~~~~

This patch will fix the issue for you:

diff --git a/tsconfig.json b/tsconfig.json
index b1937c9..6229b40 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,6 +1,7 @@
 {
     "compileOnSave": true,
     "compilerOptions": {
+      "esModuleInterop": true,
       "allowJs": true,
       "baseUrl": ".",
       "experimentalDecorators": true,

Or, since really this is an issue with the coap lib, not your code, you could use this patch to avoid type checking code you don't own:

diff --git a/tsconfig.json b/tsconfig.json
index b1937c9..5dcef04 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -2,6 +2,7 @@
     "compileOnSave": true,
     "compilerOptions": {
       "allowJs": true,
+      "skipLibCheck": true,
       "baseUrl": ".",
       "experimentalDecorators": true,
       "emitDecoratorMetadata": true,

Not a problem with lru-cache.

[isaacs]

Also, coap is using lru-cache v6 (current is v10.2.0). If they upgrade to the latest lru-cache, then they can also ditch @types/lru-cache, because the types are included.

I recommend you suggest this to them.

[JimmyBjorklund]

Thanks.