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util: add sorted option #22788

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28ffb3b
util: add order option to `.inspect()`
BridgeAR Sep 10, 2018
a8f898c
fixup: util
BridgeAR Sep 17, 2018
0ade8a7
assert: improve diff output
BridgeAR Sep 10, 2018
ea61a2f
fixup: fix assert test
BridgeAR Sep 18, 2018
779dbb0
fixup: replace `stable` with `identical`
BridgeAR Sep 18, 2018
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fixup: util
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@BridgeAR
BridgeAR committed Sep 17, 2018
commit a8f898c48986d022692d67b94d0e5fee408ded5e
39 changes: 34 additions & 5 deletions doc/api/util.md
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Expand Up @@ -429,10 +429,10 @@ changes:
objects the same as arrays. Note that no text will be reduced below 16
characters, no matter the `breakLength` size. For more information, see the
example below. **Default:** `true`.
* `sorted` {boolean|Function} If specified, the output for all object types
besides arrays and typed arrays is going to be stable. If set to `true` the
default sort is going to be used. If set to a function, it is used as
[compare function][].
* `sorted` {boolean|Function} If set to `true` or a function, all properties
of an object and Set and Map entries will be sorted in the returned string.
If set to `true` the [default sort][] is going to be used. If set to a
function, it is used as a [compare function][].
* Returns: {string} The representation of passed object

The `util.inspect()` method returns a string representation of `object` that is
Expand Down Expand Up @@ -542,6 +542,34 @@ console.log(inspect(weakSet, { showHidden: true }));
// WeakSet { { a: 1 }, { b: 2 } }
```

The `sorted` option makes sure the output is stable, no matter of the properties
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@vsemozhetbyt vsemozhetbyt Sep 17, 2018

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It seems the word stable is a bit confusing here. Compare this sentence with the wiki definition (referenced from the MDN Array.prototype.sort() page):

Stable sort algorithms sort identical elements in the same order that they appear in the input.

I.e. the traditional meaning of the stable sorting is opposite to no matter of the properties insertion order.

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@BridgeAR BridgeAR Sep 18, 2018

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True, I think I found a better wording.

insertion order:

```js
const { inspect } = require('util');
const assert = require('assert');

const o1 = {
b: [2, 3, 1],
a: '`a` comes before `b`',
c: new Set([2, 3, 1])
};
console.log(inspect(o1, { sorted: true }));
// { a: '`a` comes before `b`', b: [ 2, 3, 1 ], c: Set { 1, 2, 3 } }
console.log(inspect(o1, { sorted: (a, b) => a < b }));
// { c: Set { 3, 2, 1 }, b: [ 2, 3, 1 ], a: '`a` comes before `b`' }

const o2 = {
c: new Set([2, 1, 3]),
a: '`a` comes before `b`',
b: [2, 3, 1]
};
assert.strict.equal(
inspect(o1, { sorted: true }),
inspect(o2, { sorted: true })
);
```

Please note that `util.inspect()` is a synchronous method that is mainly
intended as a debugging tool. Its maximum output length is limited to
approximately 128 MB and input values that result in output bigger than that
Expand Down Expand Up @@ -2157,8 +2185,9 @@ Deprecated predecessor of `console.log`.
[WHATWG Encoding Standard]: https://encoding.spec.whatwg.org/
[Common System Errors]: errors.html#errors_common_system_errors
[async function]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/async_function
[compare function]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort
[compare function]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort#Parameters
[constructor]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/constructor
[default sort]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort
[global symbol registry]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/for
[list of deprecated APIS]: deprecations.html#deprecations_list_of_deprecated_apis
[semantically incompatible]: https://github.com/nodejs/node/issues/4179
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9 changes: 7 additions & 2 deletions lib/util.js
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Expand Up @@ -896,9 +896,14 @@ function formatRaw(ctx, value, recurseTimes) {
}
ctx.seen.pop();

if (ctx.sorted && extrasType === kObjectType) {
if (ctx.sorted) {
const comparator = ctx.sorted === true ? undefined : ctx.sorted;
output = output.sort(comparator);
if (extrasType === kObjectType) {
output = output.sort(comparator);
} else if (keys.length > 1) {
const sorted = output.slice(output.length - keys.length).sort(comparator);
output.splice(output.length - keys.length, keys.length, ...sorted);
}
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@jdalton jdalton Sep 12, 2018 •
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☝️ This is sorting things twice. I believe the first one, output = output.sort(), isn't needed.

}

const res = reduceToSingleString(ctx, output, base, braces);
Expand Down
14 changes: 14 additions & 0 deletions test/parallel/test-util-inspect.js
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Expand Up @@ -1691,3 +1691,17 @@ assert.strictEqual(
),
'{ a200: 4, a102: 3, a101: 2, a100: 1 }'
);

// Non-indices array properties are sorted as well.
{
const arr = [3, 2, 1];
arr.b = 2;
arr.c = 3;
arr.a = 1;
arr[Symbol('b')] = true;
arr[Symbol('a')] = false;
assert.strictEqual(
inspect(arr, { sorted: true }),
'[ 3, 2, 1, [Symbol(a)]: false, [Symbol(b)]: true, a: 1, b: 2, c: 3 ]'
);
}