fix: emit valid JS for BigInt64Array and BigUint64Array in uneval (#171)

uneval rendered typed-array elements by interpolating the array directly, which calls Array#toString and produces bare numbers (e.g. new BigInt64Array([1,2,3])). BigInt64Array/BigUint64Array constructors require bigint elements, so the emitted code threw 'Cannot convert 1 to a BigInt' when evaluated.

Emit bigint elements with an 'n' suffix. stringify/parse were unaffected (they encode the underlying buffer as base64).

Author: elliott-with-the-longest-name-on-github

.changeset/uneval-bigint-typed-array.md

@@ -0,0 +1,5 @@
+---
+"devalue": patch
+---
+
+fix: emit valid JS for `BigInt64Array` and `BigUint64Array` in `uneval`

src/uneval.js

@@ -290,8 +290,7 @@ export function uneval(value, replacer) {
 				let str = `new ${type}`;
 
 				if (!names.has(thing.buffer)) {
-					const array = new thing.constructor(thing.buffer);
-					str += `([${array}])`;
+					str += `([${stringify_typed_array_elements(new thing.constructor(thing.buffer))}])`;
 				} else {
 					str += `(${stringify(thing.buffer)})`;
 				}
@@ -445,8 +444,7 @@ export function uneval(value, replacer) {
 					let str = `new ${type}`;
 
 					if (!names.has(thing.buffer)) {
-						const array = new thing.constructor(thing.buffer);
-						str += `([${array}])`;
+						str += `([${stringify_typed_array_elements(new thing.constructor(thing.buffer))}])`;
 					} else {
 						str += `(${stringify(thing.buffer)})`;
 					}
@@ -515,6 +513,20 @@ export function uneval(value, replacer) {
 	}
 }
 
+/**
+ * Serialize the elements of a typed array as a comma-separated list.
+ * `BigInt64Array`/`BigUint64Array` elements are bigints and must be written
+ * with an `n` suffix, otherwise the emitted `new BigInt64Array([...])` throws.
+ * @param {import('./types.js').TypedArray} array
+ */
+function stringify_typed_array_elements(array) {
+	if (array instanceof BigInt64Array || array instanceof BigUint64Array) {
+		return Array.from(array, (element) => `${element}n`).join(',');
+	}
+
+	return array.toString();
+}
+
 /** @param {number} num */
 function get_name(num) {
 	let name = '';

test/index.test.js

@@ -299,6 +299,18 @@ const fixtures = {
 			js: 'new Uint8Array([1,2,3])',
 			json: '[["Uint8Array",1],["ArrayBuffer","AQID"]]'
 		},
+		{
+			name: 'BigInt64Array',
+			value: new BigInt64Array([1n, -2n, 3n]),
+			js: 'new BigInt64Array([1n,-2n,3n])',
+			json: '[["BigInt64Array",1],["ArrayBuffer","AQAAAAAAAAD+/////////wMAAAAAAAAA"]]'
+		},
+		{
+			name: 'BigUint64Array',
+			value: new BigUint64Array([1n, 2n, 3n]),
+			js: 'new BigUint64Array([1n,2n,3n])',
+			json: '[["BigUint64Array",1],["ArrayBuffer","AQAAAAAAAAACAAAAAAAAAAMAAAAAAAAA"]]'
+		},
 		{
 			name: 'ArrayBuffer',
 			value: new Uint8Array([1, 2, 3]).buffer,
@@ -739,6 +751,14 @@ const fixtures = {
 			json: '[[1,1],["DataView",2,2,4],["ArrayBuffer","AAECAwQFBgcICQ=="]]'
 		},
 
+		{
+			name: 'BigInt64Array (repetition)',
+			value: ((array) => [array, array])(new BigInt64Array([1n, 2n, 3n])),
+			js: '(function(a){a=new BigInt64Array([1n,2n,3n]);return [a,a]}({}))',
+			json: '[[1,1],["BigInt64Array",2],["ArrayBuffer","AQAAAAAAAAACAAAAAAAAAAMAAAAAAAAA"]]',
+			validate: ([a, b]) => assert.is(a, b)
+		},
+
 		{
 			name: 'Temporal.Instant (repetition)',
 			value: ((instant) => [instant, instant])(