Add safe option to guard against getters and toJSON failures

As drive-by improve the benchmark suite slightly.

Author: BridgeAR

CHANGELOG.md

@@ -1,5 +1,29 @@
 # Changelog
 
+## v2.6.0
+
+- Added `safe` option to not fail in case a getter or `.toJSON()` throws an error.
+  Instead, a string as error message is replacing the object inspection. This allows to partially inspect such objects.
+  The default is `false` to prevent any breaking change.
+
+```js
+import { configure } from 'safe-stable-stringify'
+
+const stringify = configure({
+  safe: true
+})
+
+stringify([{
+  foo: { a: 5, get foo() { throw new Error('Oops') }, c: true }
+}])
+// '[{"foo":"Error: Stringification failed. Message: Oops"}]'
+
+stringify([{
+  foo: { a: 5, toJSON() { throw new Error('Oops') }, c: true }
+}])
+// '[{"foo":"Error: Stringification failed. Message: Oops"}]'
+```
+
 ## v2.5.0
 
 - Accept `Array#sort(comparator)` comparator method as deterministic option value to use that comparator for sorting object keys.

benchmark.js

@@ -1,10 +1,9 @@
 'use strict'
 
-const Benchmark = require('benchmark')
+const Benchmark = require('bench-node')
 const suite = new Benchmark.Suite()
 const stringify = require('.').configure({ deterministic: true })
 
-// eslint-disable-next-line
 const array = Array.from({ length: 10 }, (_, i) => i)
 const obj = { array }
 const circ = JSON.parse(JSON.stringify(obj))
@@ -106,14 +105,4 @@ suite.add('indentation:   deep circular', function () {
   stringify(deepCirc, null, 2)
 })
 
-// add listeners
-suite.on('cycle', function (event) {
-  console.log(String(event.target))
-})
-
-suite.on('complete', function () {
-  console.log('\nBenchmark done')
-  // console.log('\nFastest is ' + this.filter('fastest').map('name'))
-})
-
-suite.run({ delay: 1, minSamples: 150 })
+suite.run()

compare.js

@@ -1,6 +1,6 @@
 'use strict'
 
-const Benchmark = require('benchmark')
+const Benchmark = require('bench-node')
 const suite = new Benchmark.Suite()
 const testData = require('./test.json')
 
@@ -13,7 +13,7 @@ const stringifyPackages = {
   'faster-stable-stringify': true,
   'json-stringify-deterministic': true,
   'fast-safe-stringify': 'stable',
-  this: require('.')
+  'safe-stable-stringify': require('.')
 }
 
 for (const name in stringifyPackages) {
@@ -31,9 +31,4 @@ for (const name in stringifyPackages) {
   })
 }
 
-suite
-  .on('cycle', (event) => console.log(String(event.target)))
-  .on('complete', function () {
-    console.log('\nThe fastest is ' + this.filter('fastest').map('name'))
-  })
-  .run({ async: true, delay: 5, minSamples: 150 })
+suite.run()

index.d.ts

@@ -11,6 +11,7 @@ export interface StringifyOptions {
   maximumBreadth?: number,
   maximumDepth?: number,
   strict?: boolean,
+  safe?: boolean,
 }
 
 export namespace stringify {

index.js

@@ -108,15 +108,15 @@ function getDeterministicOption (options) {
   return value === undefined ? true : value
 }
 
-function getBooleanOption (options, key) {
+function getBooleanOption (options, key, defaultValue = true) {
   let value
   if (hasOwnProperty.call(options, key)) {
     value = options[key]
     if (typeof value !== 'boolean') {
       throw new TypeError(`The "${key}" argument must be of type boolean`)
     }
   }
-  return value === undefined ? true : value
+  return value === undefined ? defaultValue : value
 }
 
 function getPositiveIntegerOption (options, key) {
@@ -169,6 +169,19 @@ function getStrictOption (options) {
   }
 }
 
+function makeSafe (method) {
+  return function (...input) {
+    try {
+      return method(...input)
+    } catch (error) {
+      const message = typeof error?.message === 'string'
+        ? error.message
+        : (() => { try { return String(error) } catch { return 'Failed' } })()
+      return strEscape('Error: Stringification failed. Message: ' + message)
+    }
+  }
+}
+
 function configure (options) {
   options = { ...options }
   const fail = getStrictOption(options)
@@ -186,8 +199,9 @@ function configure (options) {
   const comparator = typeof deterministic === 'function' ? deterministic : undefined
   const maximumDepth = getPositiveIntegerOption(options, 'maximumDepth')
   const maximumBreadth = getPositiveIntegerOption(options, 'maximumBreadth')
+  const safe = getBooleanOption(options, 'safe', false)
 
-  function stringifyFnReplacer (key, parent, stack, replacer, spacer, indentation) {
+  let stringifyFnReplacer = function (key, parent, stack, replacer, spacer, indentation) {
     let value = parent[key]
 
     if (typeof value === 'object' && value !== null && typeof value.toJSON === 'function') {
@@ -298,7 +312,7 @@ function configure (options) {
     }
   }
 
-  function stringifyArrayReplacer (key, value, stack, replacer, spacer, indentation) {
+  let stringifyArrayReplacer = function (key, value, stack, replacer, spacer, indentation) {
     if (typeof value === 'object' && value !== null && typeof value.toJSON === 'function') {
       value = value.toJSON(key)
     }
@@ -387,7 +401,7 @@ function configure (options) {
     }
   }
 
-  function stringifyIndent (key, value, stack, spacer, indentation) {
+  let stringifyIndent = function (key, value, stack, spacer, indentation) {
     switch (typeof value) {
       case 'string':
         return strEscape(value)
@@ -497,7 +511,7 @@ function configure (options) {
     }
   }
 
-  function stringifySimple (key, value, stack) {
+  let stringifySimple = function (key, value, stack) {
     switch (typeof value) {
       case 'string':
         return strEscape(value)
@@ -598,6 +612,13 @@ function configure (options) {
     }
   }
 
+  if (safe) {
+    stringifyFnReplacer = makeSafe(stringifyFnReplacer)
+    stringifyArrayReplacer = makeSafe(stringifyArrayReplacer)
+    stringifyIndent = makeSafe(stringifyIndent)
+    stringifySimple = makeSafe(stringifySimple)
+  }
+
   function stringify (value, replacer, space) {
     if (arguments.length > 1) {
       let spacer = ''

package.json

@@ -26,8 +26,8 @@
     "test": "standard && tap test.js",
     "tap": "tap test.js",
     "tap:only": "tap test.js --watch --only",
-    "benchmark": "node benchmark.js",
-    "compare": "node compare.js",
+    "benchmark": "node --allow-natives-syntax benchmark.js",
+    "compare": "node --allow-natives-syntax compare.js",
     "lint": "standard --fix",
     "tsc": "tsc --project tsconfig.json"
   },
@@ -40,7 +40,6 @@
   "devDependencies": {
     "@types/json-stable-stringify": "^1.0.34",
     "@types/node": "^18.11.18",
-    "benchmark": "^2.1.4",
     "clone": "^2.1.2",
     "fast-json-stable-stringify": "^2.1.0",
     "fast-safe-stringify": "^2.1.1",
@@ -50,6 +49,7 @@
     "json-stable-stringify": "^1.0.1",
     "json-stringify-deterministic": "^1.0.7",
     "json-stringify-safe": "^5.0.1",
+    "bench-node": "^0.5.4",
     "standard": "^16.0.4",
     "tap": "^15.0.9",
     "typescript": "^4.8.3"

readme.md

@@ -44,8 +44,8 @@ stringify(circular, ['a', 'b'], 2)
 
 ## stringify.configure(options)
 
-* `bigint` {boolean} If `true`, bigint values are converted to a number. Otherwise
-  they are ignored. **Default:** `true`.
+* `bigint` {boolean} If `true`, bigint values are converted to a number.
+  Otherwise they are ignored. **Default:** `true`.
 * `circularValue` {string|null|undefined|ErrorConstructor} Defines the value for
   circular references. Set to `undefined`, circular properties are not
   serialized (array entries are replaced with `null`). Set to `Error`, to throw
@@ -66,6 +66,9 @@ stringify(circular, ['a', 'b'], 2)
   Circular values and bigint values throw as well in case either option is not
   explicitly defined. Sets and Maps are not detected as well as Symbol keys!
   **Default:** `false`
+* `safe` {boolean} If `true`, calls to .toJSON() and getters that throw an error
+  are going to return the error message as content in place of the object
+  instead of throwing the error. **Default:** `false`
 * Returns: {function} A stringify function with the options applied.
 
 ```js

test.js

@@ -1344,3 +1344,38 @@ test('deterministic custom sorting', function (assert) {
 
   assert.end()
 })
+
+test('safe mode safeguards against failing getters', function (assert) {
+  const serializer = stringify.configure({ safe: true })
+
+  const obj = { b: 2, c: { a: true, get b () { throw new Error('Oops') } }, a: 1 }
+  const expected = '{\n "a": 1,\n "b": 2,\n "c": "Error: Stringification failed. Message: Oops"\n}'
+  const actual = serializer(obj, null, 1)
+  assert.equal(actual, expected)
+
+  assert.end()
+})
+
+test('safe mode safeguards against failing toJSON method', function (assert) {
+  const serializer = stringify.configure({ safe: true })
+
+  // eslint-disable-next-line
+  const obj = { b: 2, c: { a: true, toJSON () { throw 'Oops' } }, a: 1 }
+  const expected = '{\n "a": 1,\n "b": 2,\n "c": "Error: Stringification failed. Message: Oops"\n}'
+  const actual = serializer(obj, null, 1)
+  assert.equal(actual, expected)
+
+  assert.end()
+})
+
+test('safe mode safeguards against failing getters and a difficult to stringify error', function (assert) {
+  const serializer = stringify.configure({ safe: true })
+
+  // eslint-disable-next-line
+  const obj = { b: 2, c: { a: true, toJSON () { throw { toString() { throw new Error('Yikes') } } } }, a: 1 }
+  const expected = '{\n "a": 1,\n "b": 2,\n "c": "Error: Stringification failed. Message: Failed"\n}'
+  const actual = serializer(obj, null, 1)
+  assert.equal(actual, expected)
+
+  assert.end()
+})