Merge pull request #193 from runk/fix-assert-in-browser

fix: Warning on assert import in browser env

Author: runk

README.md

@@ -63,4 +63,16 @@ MIT
 
 ## Contributing
 
-add a link
+All contributions are welcome. Please make sure to add tests for your changes.
+
+You need to initialise the repository with the following command:
+
+```shell
+git submodule update --init --recursive
+```
+
+Then you can run tests with:
+
+```shell
+npm test
+```

src/decoder.ts

@@ -1,8 +1,7 @@
-import assert from 'assert';
 import utils from './utils';
 import { Cache } from './types';
 
-assert(
+utils.assert(
   typeof BigInt !== 'undefined',
   'Apparently you are using old version of node. Please upgrade to node 10.4.x or above.'
 );
@@ -47,7 +46,8 @@ export default class Decoder {
   private cache: Cache;
 
   constructor(db: Buffer, baseOffset = 0, cache: Cache = noCache) {
-    assert((this.db = db), 'Database buffer is required');
+    utils.assert(Boolean(db), 'Database buffer is required');
+    this.db = db;
     this.baseOffset = baseOffset;
     this.cache = cache;
   }

src/metadata.ts

@@ -1,4 +1,3 @@
-import assert from 'assert';
 import Decoder from './decoder';
 import utils from './utils';
 
@@ -35,7 +34,7 @@ export const parseMetadata = (db: Buffer): Metadata => {
     );
   }
 
-  assert(
+  utils.assert(
     [24, 28, 32].indexOf(metadata.record_size) > -1,
     'Unsupported record size'
   );

src/utils.ts

@@ -15,7 +15,14 @@ Upgrade instructions can be found here: \
 https://github.com/runk/node-maxmind/wiki/Migration-guide\n\
 If you want to use legacy library then explicitly install maxmind@1`;
 
+const assert = (condition: boolean, message: string): void => {
+  if (!condition) {
+    throw new Error(message);
+  }
+}
+
 export default {
+  assert,
   concat2,
   concat3,
   concat4,