perf: improve bigint performance with strings

This reduces the overhead for typed arrays as well as having a
faster check for cases where bigint is false.

Author: BridgeAR

CHANGELOG.md

@@ -2,6 +2,19 @@
 
 ## Next
 
+- Added `'string'` as possible `bigint` option value. Bigint values are serialized as JSON strings using it.
+
+```js
+import { configure } from 'safe-stable-stringify'
+
+const stringify = configure({
+  bigint: 'string'
+})
+
+stringify([1n, 2, 3n, 4, 5n])
+// '["1",2,"3",4,"5"]'
+```
+
 - Fixed off by one error using the `maximumBreadth` option. It showed one entry to few being skipped.
 - Added `safe` option to not fail in case a getter, `.toJSON()`, or a replacer throws an error.
   Instead, a string as error message is replacing the object inspection. This allows to partially inspect such objects.

index.js

@@ -51,6 +51,7 @@ function sort (array, comparator) {
 }
 
 const typedArrayPrototypeGetSymbolToStringTag =
+  // @ts-expect-error
   Object.getOwnPropertyDescriptor(
     Object.getPrototypeOf(
       Object.getPrototypeOf(
@@ -61,28 +62,29 @@ const typedArrayPrototypeGetSymbolToStringTag =
   ).get
 
 function isTypedArrayWithEntries (value) {
+  // @ts-expect-error
   return typedArrayPrototypeGetSymbolToStringTag.call(value) !== undefined && value.length !== 0
 }
 
+function wrapInQuotes (value) {
+  return `"${value}"`
+}
+
 function stringifyTypedArray (array, separator, maximumBreadth, bigint) {
   if (array.length < maximumBreadth) {
     maximumBreadth = array.length
   }
+  const method = bigint === 'string' && array.length > 0 && typeof array[0] === 'bigint'
+    ? wrapInQuotes
+    : String
   const whitespace = separator === ',' ? '' : ' '
-  let res = `"0":${whitespace}${formatTypedArrayValue(array[0], bigint)}`
+  let res = `"0":${whitespace}${method(array[0])}`
   for (let i = 1; i < maximumBreadth; i++) {
-    res += `${separator}"${i}":${whitespace}${formatTypedArrayValue(array[i], bigint)}`
+    res += `${separator}"${i}":${whitespace}${method(array[i])}`
   }
   return res
 }
 
-function formatTypedArrayValue (value, bigint) {
-  if (typeof value === 'bigint' && bigint === 'string') {
-    return strEscape(String(value))
-  }
-  return String(value)
-}
-
 function getCircularValueOption (options) {
   if (hasOwnProperty.call(options, 'circularValue')) {
     const circularValue = options.circularValue
@@ -353,10 +355,10 @@ function configure (options) {
       case 'undefined':
         return undefined
       case 'bigint':
-        if (bigint === 'string') {
-          return strEscape(String(value))
-        }
         if (bigint) {
+          if (bigint === 'string') {
+            return `"${String(value)}"`
+          }
           return String(value)
         }
         // fallthrough
@@ -445,10 +447,10 @@ function configure (options) {
       case 'undefined':
         return undefined
       case 'bigint':
-        if (bigint === 'string') {
-          return strEscape(String(value))
-        }
         if (bigint) {
+          if (bigint === 'string') {
+            return `"${String(value)}"`
+          }
           return String(value)
         }
         // fallthrough
@@ -558,10 +560,10 @@ function configure (options) {
       case 'undefined':
         return undefined
       case 'bigint':
-        if (bigint === 'string') {
-          return strEscape(String(value))
-        }
         if (bigint) {
+          if (bigint === 'string') {
+            return `"${String(value)}"`
+          }
           return String(value)
         }
         // fallthrough
@@ -662,10 +664,10 @@ function configure (options) {
       case 'undefined':
         return undefined
       case 'bigint':
-        if (bigint === 'string') {
-          return strEscape(String(value))
-        }
         if (bigint) {
+          if (bigint === 'string') {
+            return `"${String(value)}"`
+          }
           return String(value)
         }
         // fallthrough