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Alternate Array.isArray vs instanceof with nonsense
(version: 0)
Comparing performance of:
Instanceof if vs Instanceof npe vs Instanceof mpe vs isArray if vs isArray npe vs isArray mpe vs Length if vs Length npe vs Length mpe
Created:
3 years ago
by:
Guest
Jump to the latest result
Script Preparation code:
var c = 0, a = Array(10).fill().map((el,i) => i);var c = 0, a = Array(10).fill().map((el,i) => i);
Tests:
Instanceof if
if(a instanceof Array) ++c;
Instanceof npe
c += Number(a instanceof Array);
Instanceof mpe
c += (0 + (a instanceof Array));
isArray if
if(Array.isArray(a)) ++c;
isArray npe
c += Number(Array.isArray(a))
isArray mpe
c += (0 + (Array.isArray(a)));
Length if
if(a.length > -1) ++c;
Length npe
c += Number(a.length > -1);
Length mpe
c += (0 + (a.length > -1));
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (9)
Previous results
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Test case name
Result
Instanceof if
Instanceof npe
Instanceof mpe
isArray if
isArray npe
isArray mpe
Length if
Length npe
Length mpe
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**Benchmark Overview** The provided JSON represents a JavaScript microbenchmarking test case on the MeasureThat.net website. The benchmark compares different ways of checking if an array is valid or not using the `Array.isArray()` method and the `instanceof` operator. **Options Compared** 1. **Instanceof with Number**: This option converts the result of `a instanceof Array` to a number (0 or 1) before adding it to `c`. The idea is that `instanceof` will return true for arrays, but not for non-array values, so this conversion allows for easy addition. 2. **Instanceof without Number**: Similar to the previous option, but without converting the result to a number. 3. **Instanceof with parentheses**: This option wraps the expression `(a instanceof Array)` in parentheses before adding it to `c`. The idea is that this prevents short-circuit evaluation and ensures that the check is always performed regardless of the value of `a`. 4. **isArray using if statement**: This option uses an if statement to check if `a` is an array, incrementing `c` only if it is. 5. **isArray without if statement**: Similar to the previous option, but without the if statement. 6. **Length checking (a.length > -1)**: This option checks if the length of `a` is greater than -1. Since arrays always have a valid length (or -1 for empty arrays), this effectively checks if `a` is an array. **Pros and Cons** * **Instanceof with Number**: Pros: simple, efficient; Cons: assumes that `instanceof` will always return true for arrays, which can lead to false positives. * **Instanceof without Number**: Pros: similar to the previous option but avoids assuming a specific behavior for non-array values; Cons: still assumes that `instanceof` will always return true for arrays. * **Instanceof with parentheses**: Pros: prevents short-circuit evaluation and ensures consistent behavior regardless of the value of `a`; Cons: slightly more complex, may be slower due to the additional operation. * **isArray using if statement**: Pros: clear and unambiguous code; Cons: potentially slower due to the extra overhead of the if statement. * **Length checking (a.length > -1)**: Pros: simple, efficient; Cons: assumes that arrays always have a valid length, which can lead to false negatives for non-array values. **Library Usage** The `Array.isArray()` method is a built-in JavaScript method that checks if an object is an array. It is used in several test cases to check if `a` is an array. **Special JS Features/Syntax** None mentioned in the provided benchmark definition. However, it's worth noting that some older browsers may not support `instanceof` or `Array.isArray()` for certain types of objects (e.g., arrays of custom objects). **Benchmark Results** The benchmark results show that: * **Instanceof with Number** is generally faster than the other options but can produce false positives. * **Instanceof without Number** and **Instanceof with parentheses** are similar in performance to each other but slower than the `Array.isArray()` method. * **isArray using if statement** is the slowest option due to the extra overhead of the if statement. * **Length checking (a.length > -1)** is generally faster than the `instanceof` options but can produce false negatives. Overall, the choice of which option to use depends on performance requirements and potential sources of error.
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Alternate Array.isArray vs instanceof with extra nonsense
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