util,assert: expose util.isDeepStrictEqual()

Provide `util.isDeepStrictEqual()` that works like
`assert.deepStrictEqual()` but returns a boolean rather than throwing an
error.

Several userland modules have needed this functionality and implemented
it independently. This functionality already exists in Node.js core, so
this exposes it for use by modules. Modules that have needed this
functionality include `lodash`, `concordance` (used by `ava`), and
`qunit`.

PR-URL: https://github.com/nodejs/node/pull/16084
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

1 files changed, 16 insertions, 0 deletions

diff --git a/doc/api/util.md b/doc/api/util.md
index 6619ee2ad6..b13d02a8c0 100644
--- a/doc/api/util.md
+++ b/doc/api/util.md
@@ -455,6 +455,21 @@ util.inspect.defaultOptions.maxArrayLength = null;
 console.log(arr); // logs the full array
 ```
 
+## util.isDeepStrictEqual(val1, val2)
+<!-- YAML
+added: REPLACEME
+-->
+
+* `val1` {any}
+* `val2` {any}
+* Returns: {string}
+
+Returns `true` if there is deep strict equality between `val` and `val2`.
+Otherwise, returns `false`.
+
+See [`assert.deepStrictEqual()`][] for more information about deep strict
+equality.
+
 ## util.promisify(original)
 <!-- YAML
 added: v8.0.0
@@ -1187,6 +1202,7 @@ Deprecated predecessor of `console.log`.
 [`Buffer.isBuffer()`]: buffer.html#buffer_class_method_buffer_isbuffer_obj
 [`Error`]: errors.html#errors_class_error
 [`Object.assign()`]: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/assign
+[`assert.deepStrictEqual()`]: assert.html#assert_assert_deepstrictequal_actual_expected_message
 [`console.error()`]: console.html#console_console_error_data_args
 [`console.log()`]: console.html#console_console_log_data_args
 [`util.inspect()`]: #util_util_inspect_object_options