var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };
'd' in obj;
Object.hasOwn(obj, 'd');
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
in | |
hasOwn |
Test name | Executions per second |
---|---|
in | 39433436.0 Ops/sec |
hasOwn | 20501648.0 Ops/sec |
I'd be happy to help explain the JavaScript microbenchmark provided by MeasureThat.net.
Benchmark Overview
The benchmark compares the performance of two different ways to check if an object has a property: using the in
operator and using the hasOwn()
method. The test is designed to measure which approach is faster, but more importantly, it helps identify any potential performance bottlenecks in JavaScript code.
Options Compared
The benchmark compares the following two options:
d in obj
: This uses the in
operator to check if the object obj
has a property named d
. The in
operator checks for both the presence and value of the property.Object.hasOwn(obj, 'd')
: This uses the hasOwn()
method, which is part of the ECMAScript Object API, to check if the object obj
has a property named d
.Pros and Cons
Here are some pros and cons of each approach:
in
operator:true
if the property is a getter or setter function (not what you want in this case)hasOwn()
method:Library and Purpose
The Object.hasOwn()
method is part of the ECMAScript Object API, which provides a standardized way for objects to interact. This method checks if an object has a property with the given name.
Special JS Features or Syntax
None mentioned in this benchmark.
Other Alternatives
There are other ways to check if an object has a property, such as:
Object.prototype.hasOwnProperty()
( deprecated and removed from ECMAScript 5)if
statement: if ('d' in obj) { ... }
/^d$/
However, these alternatives are not included in this benchmark.
Benchmark Preparation Code
The preparation code for the benchmark creates an object obj
with five properties (a
, b
, c
, d
, and e
). The script to be measured is then executed using the in
operator or the hasOwn()
method, depending on the test case.
Individual Test Cases
Each test case executes a single line of code: 'd' in obj;
or Object.hasOwn(obj, 'd');
. These lines are designed to check if the object obj
has a property named d
.
The benchmark results show the performance metrics for each test case, including the number of executions per second.
I hope this explanation helps you understand what's happening in this JavaScript microbenchmark!