Benchmark: undefined vs. typeof vs. in vs. hasOwnProperty 7

Script Preparation code:

var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };
var undef = undefined;
function a() {'use strict';undef !== obj.d}
function b() {'use strict';undefined !== obj.d}
function c() {'use strict';'d' in obj}
function d() {'use strict';!!obj.d}
function e() {'use strict';'undefined' !== typeof obj.d;}
function f() {'use strict';obj.hasOwnProperty( 'd' );}

Tests:

a
a()
b
b()
c
c()
d
d()
e
e()
f
f()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
a
b
c
d
e
f

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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**Benchmark Overview**

The MeasureThat.net benchmark is designed to measure the performance of various JavaScript object lookup methods. The benchmark compares six different approaches:

1. `a()`: Uses `undef !== obj.d` (undefined comparison)
2. `b()`: Uses `undefined !== obj.d` (typeof operator with a nullish coalescing behavior)
3. `c()`: Uses `'d' in obj` (in operator)
4. `d()`: Uses `!!obj.d` (logical NOT on the boolean value of `obj.d`)
5. `e()`: Uses `'undefined' !== typeof obj.d` (typeof operator with a nullish coalescing behavior)
6. `f()`: Uses `obj.hasOwnProperty('d')` (hasOwnProperty method)

**Test Case Analysis**

Each test case measures the performance of one specific benchmark definition.

* Test cases `a`, `b`, and `e` are variants of the same comparison, with different syntax.
* Test cases `c` and `f` use different operators for object lookup: `in` and hasOwnProperty, respectively.
* Each test case is executed multiple times ( indicated by the `ExecutionsPerSecond` value) to measure performance.

**Library Usage**

None of the benchmark definitions explicitly use a library, but they do rely on built-in JavaScript features:

* The `!!` operator in test case `d()` uses the logical NOT operator (`!`) and its behavior with boolean values.
* The `typeof` operator in test cases `b`, `e`, and `a` is used with a nullish coalescing behavior, which was introduced in ECMAScript 2017.

**Pros and Cons of Each Approach**

Here's a brief analysis of each approach:

1. `a()` (`undef !== obj.d`): Simple but may be slower due to the comparison operator.
2. `b()` (`undefined !== obj.d`): Uses typeof operator with nullish coalescing behavior, which can be faster and more efficient than traditional comparisons.
3. `c()` (`'d' in obj`): In operator is generally fast and efficient for object lookup.
4. `d()` (`!!obj.d`): Logical NOT on the boolean value of `obj.d`, this approach may incur a performance penalty due to the extra operation.
5. `e()` (`'undefined' !== typeof obj.d`): Similar to `b()`, uses typeof operator with nullish coalescing behavior, but with a slightly different syntax.
6. `f()` (`obj.hasOwnProperty('d')`): HasOwnProperty method can be slower than other approaches due to its additional operation.

**Other Considerations**

* The benchmark assumes that the object `obj` is defined and has property `d`, which may not always be the case in real-world scenarios.
* The use of `typeof` operator with nullish coalescing behavior may introduce a slight performance penalty on older browsers or JavaScript engines that don't support this feature.
* The benchmark doesn't account for potential variations in performance due to other factors, such as CPU architecture, memory allocation, or caching.

**Alternatives**

If you need to perform object lookup operations with different syntax or requirements, you may consider using other approaches:

* Use the `Object.hasOwn()` method (ECMAScript 2015+) instead of `hasOwnProperty()`.
* Use a library like Lodash (`_.has()` function) for more flexible and expressive object lookup.
* Implement your own custom object lookup mechanism if performance is critical.

Related benchmarks:

undefined vs. typeof vs. in vs. hasOwnProperty 7 (version: 0)

Object lookup performance

Comparing performance of: a vs b vs c vs d vs e vs f

Created: 5 years ago by: Guest

Jump to the latest result

a

b

c

d

e

f

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):