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feat: Add native Date object support to fast-json-patch #330

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feat: Add native Date object support to fast-json-patch #330

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14 changes: 13 additions & 1 deletion commonjs/duplex.js
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Original file line number Diff line number Diff line change
Expand Up @@ -132,7 +132,19 @@ function _generate(mirror, obj, patches, path, invertible) {
if (helpers_js_1.hasOwnProperty(obj, key) && !(obj[key] === undefined && oldVal !== undefined && Array.isArray(obj) === false)) {
var newVal = obj[key];
if (typeof oldVal == "object" && oldVal != null && typeof newVal == "object" && newVal != null && Array.isArray(oldVal) === Array.isArray(newVal)) {
_generate(oldVal, newVal, patches, path + "/" + helpers_js_1.escapePathComponent(key), invertible);
// Special handling for Date objects: compare by value, not reference
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@chakrabar chakrabar Nov 11, 2025 •
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if structuredClone is available, maybe we can use that, otherwise fallback to this?

if (oldVal instanceof Date && newVal instanceof Date) {
if (oldVal.getTime() !== newVal.getTime()) {
changed = true;
if (invertible) {
patches.push({ op: "test", path: path + "/" + helpers_js_1.escapePathComponent(key), value: helpers_js_1._deepClone(oldVal) });
}
patches.push({ op: "replace", path: path + "/" + helpers_js_1.escapePathComponent(key), value: helpers_js_1._deepClone(newVal) });
}
}
else {
_generate(oldVal, newVal, patches, path + "/" + helpers_js_1.escapePathComponent(key), invertible);
}
}
else {
if (oldVal !== newVal) {
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20 changes: 19 additions & 1 deletion commonjs/helpers.js
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,25 @@ exports._objectKeys = _objectKeys;
function _deepClone(obj) {
switch (typeof obj) {
case "object":
return JSON.parse(JSON.stringify(obj)); //Faster than ES5 clone - http://jsperf.com/deep-cloning-of-objects/5
if (obj === null) {
return null;
}
// Handle Date objects specially to preserve them as Date instances
if (obj instanceof Date) {
return new Date(obj.getTime());
}
// Handle Arrays
if (Array.isArray(obj)) {
return obj.map(function (item) { return _deepClone(item); });
}
// Handle plain objects - recursively clone each property
var cloned = {};
for (var key in obj) {
if (hasOwnProperty(obj, key)) {
cloned[key] = _deepClone(obj[key]);
}
}
return cloned;
case "undefined":
return null; //this is how JSON.stringify behaves for array items
default:
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14 changes: 13 additions & 1 deletion module/duplex.mjs
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Original file line number Diff line number Diff line change
Expand Up @@ -128,7 +128,19 @@ function _generate(mirror, obj, patches, path, invertible) {
if (hasOwnProperty(obj, key) && !(obj[key] === undefined && oldVal !== undefined && Array.isArray(obj) === false)) {
var newVal = obj[key];
if (typeof oldVal == "object" && oldVal != null && typeof newVal == "object" && newVal != null && Array.isArray(oldVal) === Array.isArray(newVal)) {
_generate(oldVal, newVal, patches, path + "/" + escapePathComponent(key), invertible);
// Special handling for Date objects: compare by value, not reference
if (oldVal instanceof Date && newVal instanceof Date) {
if (oldVal.getTime() !== newVal.getTime()) {
changed = true;
if (invertible) {
patches.push({ op: "test", path: path + "/" + escapePathComponent(key), value: _deepClone(oldVal) });
}
patches.push({ op: "replace", path: path + "/" + escapePathComponent(key), value: _deepClone(newVal) });
}
}
else {
_generate(oldVal, newVal, patches, path + "/" + escapePathComponent(key), invertible);
}
}
else {
if (oldVal !== newVal) {
Expand Down
20 changes: 19 additions & 1 deletion module/helpers.mjs
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Original file line number Diff line number Diff line change
Expand Up @@ -49,7 +49,25 @@ export function _objectKeys(obj) {
export function _deepClone(obj) {
switch (typeof obj) {
case "object":
return JSON.parse(JSON.stringify(obj)); //Faster than ES5 clone - http://jsperf.com/deep-cloning-of-objects/5
if (obj === null) {
return null;
}
// Handle Date objects specially to preserve them as Date instances
if (obj instanceof Date) {
return new Date(obj.getTime());
}
// Handle Arrays
if (Array.isArray(obj)) {
return obj.map(function (item) { return _deepClone(item); });
}
// Handle plain objects - recursively clone each property
var cloned = {};
for (var key in obj) {
if (hasOwnProperty(obj, key)) {
cloned[key] = _deepClone(obj[key]);
}
}
return cloned;
case "undefined":
return null; //this is how JSON.stringify behaves for array items
default:
Expand Down
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