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perf(arrays): defer index string conversion #75

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Merged
BridgeAR merged 1 commit into from
Oct 13, 2026
Merged

perf(arrays): defer index string conversion #75

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69 changes: 47 additions & 22 deletions index.js
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,8 @@

const { hasOwnProperty } = Object.prototype

/** @typedef {{toJSON: (key: string) => unknown}} ToJSON */

const stringify = configure()

// @ts-expect-error
Expand Down Expand Up @@ -394,9 +396,18 @@ function configure (options) {
}
}

/**
* @param {string | number} key
* @param {unknown} value
* @param {object[]} stack
* @param {Set<string>} replacer
* @param {string} spacer
* @param {string} indentation
*/
let stringifyArrayReplacer = function (key, value, stack, replacer, spacer, indentation) {
if (typeof value === 'object' && value !== null && typeof value.toJSON === 'function') {
value = safe ? callSafe(value.toJSON, value, key) : value.toJSON(key)
if (typeof value === 'object' && value !== null && typeof /** @type {ToJSON} */ (value).toJSON === 'function') {
if (typeof key === 'number') key = String(key)
value = safe ? callSafe(/** @type {ToJSON} */ (value).toJSON, value, key) : /** @type {ToJSON} */ (value).toJSON(key)
}

switch (typeof value) {
Expand Down Expand Up @@ -431,11 +442,11 @@ function configure (options) {
const maximumValuesToStringify = Math.min(value.length, maximumBreadth)
let i = 0
for (; i < maximumValuesToStringify - 1; i++) {
const tmp = stringifyArrayReplacer(String(i), value[i], stack, replacer, spacer, indentation)
const tmp = stringifyArrayReplacer(i, value[i], stack, replacer, spacer, indentation)
res += tmp !== undefined ? tmp : 'null'
res += join
}
const tmp = stringifyArrayReplacer(String(i), value[i], stack, replacer, spacer, indentation)
const tmp = stringifyArrayReplacer(i, value[i], stack, replacer, spacer, indentation)
res += tmp !== undefined ? tmp : 'null'
if (value.length > maximumBreadth) {
const removedKeys = value.length - maximumBreadth
Expand All @@ -459,7 +470,7 @@ function configure (options) {
}
let separator = ''
for (const key of replacer) {
const tmp = stringifyArrayReplacer(key, value[key], stack, replacer, spacer, indentation)
const tmp = stringifyArrayReplacer(key, /** @type {Record<string, unknown>} */ (value)[key], stack, replacer, spacer, indentation)
if (tmp !== undefined) {
res += `${separator}${strEscape(key)}:${whitespace}${tmp}`
separator = join
Expand Down Expand Up @@ -490,6 +501,13 @@ function configure (options) {
}
}

/**
* @param {string | number} key
* @param {unknown} value
* @param {object[]} stack
* @param {string} spacer
* @param {string} indentation
*/
let stringifyIndent = function (key, value, stack, spacer, indentation) {
switch (typeof value) {
case 'string':
Expand All @@ -498,8 +516,9 @@ function configure (options) {
if (value === null) {
return 'null'
}
if (typeof value.toJSON === 'function') {
value = safe ? callSafe(value.toJSON, value, key) : value.toJSON(key)
if (typeof /** @type {ToJSON} */ (value).toJSON === 'function') {
if (typeof key === 'number') key = String(key)
value = safe ? callSafe(/** @type {ToJSON} */ (value).toJSON, value, key) : /** @type {ToJSON} */ (value).toJSON(key)
// Prevent calling `toJSON` again.
if (typeof value !== 'object') {
return stringifyIndent(key, value, stack, spacer, indentation)
Expand Down Expand Up @@ -528,11 +547,11 @@ function configure (options) {
const maximumValuesToStringify = Math.min(value.length, maximumBreadth)
let i = 0
for (; i < maximumValuesToStringify - 1; i++) {
const tmp = stringifyIndent(String(i), value[i], stack, spacer, indentation)
const tmp = stringifyIndent(i, value[i], stack, spacer, indentation)
res += tmp !== undefined ? tmp : 'null'
res += join
}
const tmp = stringifyIndent(String(i), value[i], stack, spacer, indentation)
const tmp = stringifyIndent(i, value[i], stack, spacer, indentation)
res += tmp !== undefined ? tmp : 'null'
if (value.length > maximumBreadth) {
const removedKeys = value.length - maximumBreadth
Expand All @@ -558,9 +577,9 @@ function configure (options) {
let maximumPropertiesToStringify = Math.min(keyLength, maximumBreadth)
const typedArrayType = getTypedArrayType(value)
if (typedArrayType !== undefined) {
res += stringifyTypedArray(value, join, maximumBreadth, bigint, fail, typedArrayType)
keys = keys.slice(value.length)
maximumPropertiesToStringify -= value.length
res += stringifyTypedArray(/** @type {ArrayLike<number | bigint>} */ (value), join, maximumBreadth, bigint, fail, typedArrayType)
keys = keys.slice(/** @type {{length: number}} */ (value).length)
maximumPropertiesToStringify -= /** @type {{length: number}} */ (value).length
separator = join
}
if (deterministic) {
Expand All @@ -569,7 +588,7 @@ function configure (options) {
stack.push(value)
for (let i = 0; i < maximumPropertiesToStringify; i++) {
const key = keys[i]
const tmp = stringifyIndent(key, value[key], stack, spacer, indentation)
const tmp = stringifyIndent(key, /** @type {Record<string, unknown>} */ (value)[key], stack, spacer, indentation)
if (tmp !== undefined) {
res += `${separator}${strEscape(key)}: ${tmp}`
separator = join
Expand Down Expand Up @@ -605,6 +624,11 @@ function configure (options) {
}
}

/**
* @param {string | number} key
* @param {unknown} value
* @param {object[]} stack
*/
let stringifySimple = function (key, value, stack) {
switch (typeof value) {
case 'string':
Expand All @@ -613,8 +637,9 @@ function configure (options) {
if (value === null) {
return 'null'
}
if (typeof value.toJSON === 'function') {
value = safe ? callSafe(value.toJSON, value, key) : value.toJSON(key)
if (typeof /** @type {ToJSON} */ (value).toJSON === 'function') {
if (typeof key === 'number') key = String(key)
value = safe ? callSafe(/** @type {ToJSON} */ (value).toJSON, value, key) : /** @type {ToJSON} */ (value).toJSON(key)
// Prevent calling `toJSON` again
if (typeof value !== 'object') {
return stringifySimple(key, value, stack)
Expand All @@ -630,7 +655,7 @@ function configure (options) {

let res = ''

const hasLength = value.length !== undefined
const hasLength = /** @type {{length?: unknown}} */ (value).length !== undefined
if (hasLength && Array.isArray(value)) {
if (value.length === 0) {
return '[]'
Expand All @@ -642,11 +667,11 @@ function configure (options) {
const maximumValuesToStringify = Math.min(value.length, maximumBreadth)
let i = 0
for (; i < maximumValuesToStringify - 1; i++) {
const tmp = stringifySimple(String(i), value[i], stack)
const tmp = stringifySimple(i, value[i], stack)
res += tmp !== undefined ? tmp : 'null'
res += ','
}
const tmp = stringifySimple(String(i), value[i], stack)
const tmp = stringifySimple(i, value[i], stack)
res += tmp !== undefined ? tmp : 'null'
if (value.length > maximumBreadth) {
const removedKeys = value.length - maximumBreadth
Expand All @@ -668,9 +693,9 @@ function configure (options) {
let maximumPropertiesToStringify = Math.min(keyLength, maximumBreadth)
const typedArrayType = hasLength ? getTypedArrayType(value) : undefined
if (typedArrayType !== undefined) {
res += stringifyTypedArray(value, ',', maximumBreadth, bigint, fail, typedArrayType)
keys = keys.slice(value.length)
maximumPropertiesToStringify -= value.length
res += stringifyTypedArray(/** @type {ArrayLike<number | bigint>} */ (value), ',', maximumBreadth, bigint, fail, typedArrayType)
keys = keys.slice(/** @type {{length: number}} */ (value).length)
maximumPropertiesToStringify -= /** @type {{length: number}} */ (value).length
separator = ','
}
if (deterministic) {
Expand All @@ -679,7 +704,7 @@ function configure (options) {
stack.push(value)
for (let i = 0; i < maximumPropertiesToStringify; i++) {
const key = keys[i]
const tmp = stringifySimple(key, value[key], stack)
const tmp = stringifySimple(key, /** @type {Record<string, unknown>} */ (value)[key], stack)
if (tmp !== undefined) {
res += `${separator}${strEscape(key)}:${tmp}`
separator = ','
Expand Down
69 changes: 45 additions & 24 deletions test.js
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -217,29 +217,47 @@ test('circular depths can have multiple digits', /** @param {import('tap').Test}
assert.end()
})

test('toJSON receives array keys as string', function (assert) {
const object = [{
toJSON (key) {
assert.equal(key, '0')
return 42
test('toJSON receives array keys as string', /** @param {import('tap').Test} assert */ (assert) => {
for (const safe of [false, true]) {
const serializer = stringify.configure({ safe })
for (const replacer of [undefined, identityReplacer, ['nested']]) {
for (const space of [undefined, 2]) {
const keys = []
const array = new Array(1001)
for (const index of [0, 10, 1000]) {
array[index] = {
/** @param {string} key */
toJSON (key) {
keys.push(key)
return index
}
}
}
array[1] = {
/** @param {string} key */
toJSON (key) {
keys.push(key)
return {
nested: [{
/** @param {string} key */
toJSON (key) {
keys.push(key)
return null
}
}]
}
}
}
const expected = new Array(1001)
expected[0] = 0
expected[1] = { nested: [null] }
expected[10] = 10
expected[1000] = 1000
assert.equal(serializer(array, replacer, space), JSON.stringify(expected, null, space))
assert.strictSame(keys, ['0', '1', '0', '10', '1000'])
}
}
}]

const expected = JSON.stringify(object)

let actual = stringify(object)
assert.equal(actual, expected)

actual = stringify(object, ['0'])
assert.equal(actual, expected)

// @ts-expect-error
actual = stringify(object, (key, value) => value)
assert.equal(actual, expected)

actual = stringify(object, null, 2)
assert.equal(actual, '[\n 42\n]')

}
assert.end()
})

Expand Down Expand Up @@ -800,8 +818,10 @@ test('bigint option as string', function (assert) {
assert.end()
})

test('bigint option invalid values', function (assert) {
test('bigint option invalid values', /** @param {import('tap').Test} assert */ function (assert) {
// @ts-expect-error
assert.throws(() => stringify.configure({ bigint: 'nope' }), /bigint/)
// @ts-expect-error
assert.throws(() => stringify.configure({ bigint: 1 }), /bigint/)
assert.end()
})
Expand Down Expand Up @@ -1613,7 +1633,8 @@ test('safe option defaults and explicit false', function (assert) {
assert.end()
})

test('safe option must be boolean', function (assert) {
test('safe option must be boolean', /** @param {import('tap').Test} assert */ function (assert) {
// @ts-expect-error
assert.throws(() => stringify.configure({ safe: 'yes' }), /safe/)
assert.end()
})
Expand Down
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