Use lazy hex cache

Author: SeanReece

src/objectid.ts

@@ -32,7 +32,7 @@ export class ObjectId extends BSONValue {
   /** @internal */
   private static index = Math.floor(Math.random() * 0xffffff);
 
-  static cacheHexString: boolean;
+  static cacheHexString: boolean = true;
 
   /** ObjectId Bytes @internal */
   private buffer!: Uint8Array;
@@ -111,6 +111,10 @@ export class ObjectId extends BSONValue {
     } else if (typeof workingId === 'string') {
       if (ObjectId.validateHexString(workingId)) {
         this.buffer = ByteUtils.fromHex(workingId);
+        // If we are caching the hex string
+        if (ObjectId.cacheHexString) {
+          this.__id = workingId;
+        }
       } else {
         throw new BSONError(
           'input must be a 24 character hex string, 12 byte Uint8Array, or an integer'
@@ -119,10 +123,6 @@ export class ObjectId extends BSONValue {
     } else {
       throw new BSONError('Argument passed in does not match the accepted types');
     }
-    // If we are caching the hex string
-    if (ObjectId.cacheHexString) {
-      this.__id = ByteUtils.toHex(this.id);
-    }
   }
 
   /**

test/node/bson_test.js

@@ -1648,21 +1648,25 @@ describe('BSON', function () {
   it('ObjectId should have a correct cached representation of the hexString', function (done) {
     ObjectId.cacheHexString = true;
     var a = new ObjectId();
+    a.toHexString();
     var __id = a.__id;
     expect(__id).to.equal(a.toHexString());
 
     // hexString
     a = new ObjectId(__id);
+    a.toHexString();
     expect(__id).to.equal(a.toHexString());
 
     // fromHexString
     a = ObjectId.createFromHexString(__id);
+    a.toHexString();
     expect(a.__id).to.equal(a.toHexString());
     expect(__id).to.equal(a.toHexString());
 
     // number
     var genTime = a.generationTime;
     a = new ObjectId(genTime);
+    a.toHexString();
     __id = a.__id;
     expect(__id).to.equal(a.toHexString());
 
@@ -1673,6 +1677,7 @@ describe('BSON', function () {
 
     // createFromTime
     a = ObjectId.createFromTime(genTime);
+    a.toHexString();
     __id = a.__id;
     expect(__id).to.equal(a.toHexString());
     ObjectId.cacheHexString = false;
@@ -1861,7 +1866,7 @@ describe('BSON', function () {
         );
         expect(inspect(code)).to.equal(
           /* eslint-disable */
-`new Code(
+          `new Code(
 'function iLoveJavaScript() {\\n' +
   '            do {\\n' +
   "              console.log('hello!');\\n" +