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feat: add comparison of functions by content #115

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feat: add comparison of functions by content #115

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28 changes: 12 additions & 16 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -18,8 +18,7 @@ function equal(a, b) {
if (Array.isArray(a)) {
length = a.length;
if (length != b.length) return false;
for (i = length; i-- !== 0;)
if (!equal(a[i], b[i])) return false;
for (i = length; i-- !== 0; ) if (!equal(a[i], b[i])) return false;
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Sorry, it looks like my IDE prettier settings did a bit of reformatting here. If there's a particular code style that's meant to be followed, would be good to get a prettier config into the repo

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As the source code comments indicate, we track upstream source code from https://github.com/epoberezkin/fast-deep-equal and then place our updates inside. Community PRs usually just attempt to update our specific modifications here or update the upstream library first.

return true;
}

Expand All @@ -44,31 +43,27 @@ function equal(a, b) {
//
// **Note**: `i` access switches to `i.value`.
var it;
if (hasMap && (a instanceof Map) && (b instanceof Map)) {
if (hasMap && a instanceof Map && b instanceof Map) {
if (a.size !== b.size) return false;
it = a.entries();
while (!(i = it.next()).done)
if (!b.has(i.value[0])) return false;
while (!(i = it.next()).done) if (!b.has(i.value[0])) return false;
it = a.entries();
while (!(i = it.next()).done)
if (!equal(i.value[1], b.get(i.value[0]))) return false;
while (!(i = it.next()).done) if (!equal(i.value[1], b.get(i.value[0]))) return false;
return true;
}

if (hasSet && (a instanceof Set) && (b instanceof Set)) {
if (hasSet && a instanceof Set && b instanceof Set) {
if (a.size !== b.size) return false;
it = a.entries();
while (!(i = it.next()).done)
if (!b.has(i.value[0])) return false;
while (!(i = it.next()).done) if (!b.has(i.value[0])) return false;
return true;
}
// END: Modifications

if (hasArrayBuffer && ArrayBuffer.isView(a) && ArrayBuffer.isView(b)) {
length = a.length;
if (length != b.length) return false;
for (i = length; i-- !== 0;)
if (a[i] !== b[i]) return false;
for (i = length; i-- !== 0; ) if (a[i] !== b[i]) return false;
return true;
}

Expand All @@ -80,16 +75,15 @@ function equal(a, b) {
length = keys.length;
if (length !== Object.keys(b).length) return false;

for (i = length; i-- !== 0;)
if (!Object.prototype.hasOwnProperty.call(b, keys[i])) return false;
for (i = length; i-- !== 0; ) if (!Object.prototype.hasOwnProperty.call(b, keys[i])) return false;
// END: fast-deep-equal

// START: react-fast-compare
// custom handling for DOM elements
if (hasElementType && a instanceof Element) return false;

// custom handling for React/Preact
for (i = length; i-- !== 0;) {
for (i = length; i-- !== 0; ) {
if ((keys[i] === '_owner' || keys[i] === '__v' || keys[i] === '__o') && a.$$typeof) {
// React-specific: avoid traversing React elements' _owner
// Preact-specific: avoid traversing Preact elements' __v and __o
Expand All @@ -111,6 +105,8 @@ function equal(a, b) {
return true;
}

if (typeof a === 'function' && typeof b === 'function') return a.toString() === b.toString();

return a !== a && b !== b;
}
// end fast-deep-equal
Expand All @@ -119,7 +115,7 @@ module.exports = function isEqual(a, b) {
try {
return equal(a, b);
} catch (error) {
if (((error.message || '').match(/stack|recursion/i))) {
if ((error.message || '').match(/stack|recursion/i)) {
// warn on circular references, don't crash
// browsers give this different errors name and messages:
// chrome/safari: "RangeError", "Maximum call stack size exceeded"
Expand Down
57 changes: 43 additions & 14 deletions test/node/tests.js
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Original file line number Diff line number Diff line change
Expand Up @@ -3,40 +3,39 @@ var generic = require('fast-deep-equal-git/spec/tests.js');
var es6 = require('fast-deep-equal-git/spec/es6tests.js');

const reactElementA = {
'$$typeof': 'react.element',
$$typeof: 'react.element',
type: 'div',
key: null,
ref: null,
props: { x: 1 },
_owner: {},
_store: {}
_store: {},
};
// in reality the _owner object is much more complex (and contains over dozen circular references)
reactElementA._owner.children = [reactElementA];

const reactElementA2 = {
'$$typeof': 'react.element',
$$typeof: 'react.element',
type: 'div',
key: null,
ref: null,
props: { x: 1 },
_owner: {},
_store: {}
_store: {},
};
reactElementA2._owner.children = [reactElementA2];

const reactElementB = {
'$$typeof': 'react.element',
$$typeof: 'react.element',
type: 'div',
key: null,
ref: null,
props: { x: 2 },
_owner: {},
_store: {}
_store: {},
};
reactElementB._owner.children = [reactElementB];


const react = [
{
description: 'React elements',
Expand All @@ -46,27 +45,57 @@ const react = [
description: 'an element compared with itself',
value1: reactElementA,
value2: reactElementA,
equal: true
equal: true,
},
{
description: 'two elements equal by value',
value1: reactElementA,
value2: reactElementA2,
equal: true
equal: true,
},
{
description: 'two elements unequal by value',
value1: reactElementA,
value2: reactElementB,
equal: false
}
]
}
equal: false,
},
],
},
];

const exampleFn = () => 'foo';

const functions = [
{
description: 'Functions',
reactSpecific: false,
tests: [
{
description: 'a function compared with itself',
value1: exampleFn,
value2: exampleFn,
equal: true,
},
{
description: 'two equal inline functions',
value1: () => 'foo',
value2: () => 'foo',
equal: true,
},
{
description: 'two functions with different results',
value1: () => 'foo',
value2: () => 'bar',
equal: false,
},
],
},
];

module.exports = {
generic,
es6,
react,
all: [...generic, ...es6, ...react],
functions,
all: [...generic, ...es6, ...react, ...functions],
};