Merge pull request #43 from haines/syntax-errors

Throw syntax errors when parsing invalid input

Author: Rich-Harris

src/parse.js

@@ -14,19 +14,26 @@ import {
 export function parse(serialized) {
 	const parsed = JSON.parse(serialized);
 
-	if (typeof parsed === 'number') return hydrate(parsed);
+	if (typeof parsed === 'number') return hydrate(parsed, true);
+
+	if (!Array.isArray(parsed) || parsed.length === 0) {
+		throw new Error('Invalid input');
+	}
 
 	const values = /** @type {any[]} */ (parsed);
+
 	const hydrated = Array(values.length);
 
 	/** @param {number} index */
-	function hydrate(index) {
+	function hydrate(index, standalone = false) {
 		if (index === UNDEFINED) return undefined;
 		if (index === NAN) return NaN;
 		if (index === POSITIVE_INFINITY) return Infinity;
 		if (index === NEGATIVE_INFINITY) return -Infinity;
 		if (index === NEGATIVE_ZERO) return -0;
 
+		if (standalone) throw new Error(`Invalid input`);
+
 		if (index in hydrated) return hydrated[index];
 
 		const value = values[index];

test/test.js

@@ -406,6 +406,63 @@ for (const [name, tests] of Object.entries(fixtures)) {
 	test.run();
 }
 
+const invalid = [
+	{
+		name: 'empty string',
+		json: '',
+		message: 'Unexpected end of JSON input'
+	},
+	{
+		name: 'invalid JSON',
+		json: '][',
+		message: 'Unexpected token ] in JSON at position 0'
+	},
+	{
+		name: 'hole',
+		json: '-2',
+		message: 'Invalid input'
+	},
+	{
+		name: 'string',
+		json: '"hello"',
+		message: 'Invalid input'
+	},
+	{
+		name: 'number',
+		json: '42',
+		message: 'Invalid input'
+	},
+	{
+		name: 'boolean',
+		json: 'true',
+		message: 'Invalid input'
+	},
+	{
+		name: 'null',
+		json: 'null',
+		message: 'Invalid input'
+	},
+	{
+		name: 'object',
+		json: '{}',
+		message: 'Invalid input'
+	},
+	{
+		name: 'empty array',
+		json: '[]',
+		message: 'Invalid input'
+	}
+];
+
+for (const { name, json, message } of invalid) {
+	uvu.test(`parse error: ${name}`, () => {
+		assert.throws(
+			() => parse(json),
+			(error) => error.message === message
+		);
+	});
+}
+
 for (const fn of [uneval, stringify]) {
 	uvu.test(`${fn.name} throws for non-POJOs`, () => {
 		class Foo {}