window.obj = undefined
window.obj === undefined
typeof window.obj === 'undefined'
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
equality | |
typeof |
Test name | Executions per second |
---|---|
equality | 3758646.0 Ops/sec |
typeof | 7264546.5 Ops/sec |
Let's dive into the world of JavaScript microbenchmarks.
The provided JSON represents a benchmark test on MeasureThat.net, which compares two approaches to check if undefined
is present in the variable window.obj
. Here's a breakdown of what's being tested and compared:
Test Case 1: Equality Check (window.obj === undefined
)
window.obj
and undefined
, using the triple equals (===
) operator.Test Case 2: Type Check with typeof
(typeof window.obj === 'undefined'
)
window.obj
is 'undefined'
, using the typeof
operator.Now, let's discuss the pros and cons of each approach:
Equality Check (window.obj === undefined
)
Pros:
undefined
, which can be more intuitive.Cons:
undefined
.Type Check with typeof
(typeof window.obj === 'undefined'
)
Pros:
typeof
operator explicitly states the type of the variable, making it clearer what's being checked.Cons:
typeof
differently than equality checks.Library and Special Features
There are no libraries mentioned in the provided benchmark definition. However, it's worth noting that some JavaScript implementations (e.g., Safari) have specific optimizations for certain types of checks or operators.
Other Alternatives
If you're interested in exploring alternative approaches to this benchmark, consider the following:
undefined
. This approach might be more accurate but could also be slower.window.obj
is undefined
. This approach would be slower than equality checks but could provide more insight into the object's structure.Keep in mind that these alternatives might not be suitable for this specific benchmark or might require significant modifications to the original test.