_tils/2021-08-11-encoding-and-decoding-javascript-bigint-values-with-reviver.md: Use regex to make the reviver dramatically simpler

1 files changed, 13 insertions, 20 deletions

diff --git a/_tils/2021-08-11-encoding-and-decoding-javascript-bigint-values-with-reviver.md b/_tils/2021-08-11-encoding-and-decoding-javascript-bigint-values-with-reviver.md
index f309641..d71174d 100644
--- a/_tils/2021-08-11-encoding-and-decoding-javascript-bigint-values-with-reviver.md
+++ b/_tils/2021-08-11-encoding-and-decoding-javascript-bigint-values-with-reviver.md
@@ -4,6 +4,8 @@ title: Encoding and decoding JavaScript BigInt values with reviver
 
 date: 2021-08-11
 
+updated_at: 2021-08-13
+
 layout: post
 
 lang: en
@@ -24,19 +26,10 @@ and encode JavaScript `BigInt` numbers via JSON:
 [`BigInt`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt
 
 ```javascript
-const bigIntReviver = (_, value) => {
-	if (
-		   typeof value === "string"
-		&& value[value.length - 1] === "n"
-		&& value.length > 1
-	) {
-		const numberStr = value.slice(0, value.length - 1);
-		if (numberStr.match(/^[0-9]+$/) !== null) {
-			return BigInt(numberStr);
-		}
-	}
-	return value;
-};
+const bigIntReviver = (_, value) =>
+	typeof value === "string" && value.match(/^-?[0-9]+n$/)
+		? BigInt(value.slice(0, value.length - 1))
+		: value;
 ```
 
 I chose to interpret strings that contains only numbers and an ending `n` suffix
@@ -44,8 +37,8 @@ as `BigInt` values, similar to how JavaScript interprets `123` (a number)
 differently from `123n` (a `bigint`);
 
 We do those checks before constructing the `BigInt` to avoid throwing needless
-exceptions on the parsing function, as this could easily become a bottleneck
-when parsing large JSON values.
+exceptions and catching them on the parsing function, as this could easily
+become a bottleneck when parsing large JSON values.
 
 In order to do the full roundtrip, we now only need the `toJSON()` counterpart:
 
@@ -66,8 +59,8 @@ const s = `[
 	-1,
 	3.14,
 	"a string",
-	{ "a-number": "123" },
-	{ "a-bigint": "123n" }
+	{ "a-number": "-123" },
+	{ "a-bigint": "-123n" }
 ]`;
 
 const parsed = JSON.parse(s, bigIntReviver);
@@ -90,10 +83,10 @@ The output of the above is:
   -1,
   3.14,
   'a string',
-  { 'a-number': '123' },
-  { 'a-bigint': 123n }
+  { 'a-number': '-123' },
+  { 'a-bigint': -123n }
 ]
-[null,true,false,-1,3.14,"a string",{"a-number":"123"},{"a-bigint":"123n"}]
+[null,true,false,-1,3.14,"a string",{"a-number":"-123"},{"a-bigint":"-123n"}]
 string
 bigint
 ```