Benchmark: undefined - MeasureThat.net

undefined (version: 0)

undefined js

Comparing performance of: undefined w/ type vs undefined w/o type without type check vs typeof equal to vs typeof equal to without type check vs with brackets around typeof unequal vs with brackets around typeof equal vs with brackets around typeof unequal with type check vs with brackets around typeof equal with type check

Created: 6 years ago by: Guest

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Script Preparation code:

var obj = {};

Tests:

undefined w/ type
'undefined' !== typeof obj.d;
undefined w/o type without type check
'undefined' != typeof obj.d;
typeof equal to
typeof(obj.d) == 'undefined'
typeof equal to without type check
typeof(obj.d) === 'undefined'
with brackets around typeof unequal
typeof(obj.d) != 'undefined'
with brackets around typeof equal
typeof(obj.d) == 'undefined'
with brackets around typeof unequal with type check
typeof(obj.d) !== 'undefined'
with brackets around typeof equal with type check
typeof(obj.d) === 'undefined'

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined w/ type
undefined w/o type without type check
typeof equal to
typeof equal to without type check
with brackets around typeof unequal
with brackets around typeof equal
with brackets around typeof unequal with type check
with brackets around typeof equal with type check

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases.

**What is tested?**

The benchmark tests different variations of JavaScript code that check if the `typeof` operator returns `'undefined'`, `'equal to'`, or `'unequal'` when used with the value `obj.d`. The `obj` variable is initialized as an empty object `{}`.

**Options compared:**

The benchmark compares four options:

1. **`'undefined' !== typeof obj.d`**: Checks if `typeof obj.d` returns `'undefined'`.
2. **`'undefined' != typeof obj.d`**: Similar to the previous one, but without type checking.
3. **`typeof(obj.d) == 'undefined'`**: Checks if `typeof obj.d` returns the string `'undefined'`.
4. **`typeof(obj.d) === 'undefined'`**: Similar to the previous one, with type checking.

**Pros and Cons:**

1. **No brackets around `typeof`**:
	* Pros: More readable and concise syntax.
	* Cons: May lead to unexpected behavior if not used correctly (e.g., in certain edge cases).
2. **With brackets around `typeof`**:
	* Pros: Ensures that the type check is performed, preventing potential issues with inconsistent type coercion.
	* Cons: Less readable and more verbose syntax.

In general, using brackets around `typeof` provides a layer of protection against unexpected behavior, but it may come at the cost of readability. Without brackets, the syntax is more concise, but it requires careful attention to ensure that the comparison is performed correctly.

**Library usage:**

The benchmark does not use any external libraries or frameworks. The code only relies on built-in JavaScript features and operators.

**Special JS features or syntax:**

There are no special JavaScript features or syntax used in this benchmark. It solely focuses on testing the `typeof` operator with different variations of comparisons.

**Other alternatives:**

If you wanted to write a similar benchmark, here are some alternative options:

1. Use a more explicit comparison instead of relying on the `typeof` operator:
```javascript
obj.d = null;
console.log(obj.d === null); // true
```
2. Test the behavior with different data types (e.g., numbers, strings, booleans):
```javascript
const obj = {};
obj.a = 123;
console.log(typeof obj.a); // "number"
```
3. Use a different approach to check if a variable is undefined:
```javascript
const obj = { d: null };
if (!obj.d) {
    console.log("d is undefined");
}
```

Keep in mind that these alternatives would require significant changes to the benchmark definition and test cases.

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