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Test if key is in object.
(version: 0)
Comparing performance of:
Lookup Map vs Object dot vs Object in
Created:
3 years ago
by:
Guest
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Script Preparation code:
var entries = new Array(1000).fill(0).map((_, i) => ['id_'+i, true]); var obj = Object.fromEntries(entries); var map = new Map(entries);
Tests:
Lookup Map
let hasKey = map.has('id_900');
Object dot
let hasKey = !!obj['id_900'];
Object in
let hasKey = 'id_900' in obj;
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
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Test case name
Result
Lookup Map
Object dot
Object in
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark and explain what is tested, the options compared, their pros and cons, and other considerations. **Benchmark Overview** The benchmark measures the performance of three different ways to check if a key exists in an object or map: 1. **Lookup Map**: Using the `has()` method on a `Map` object. 2. **Object dot**: Using the property access syntax (`obj['id_900']`) to access the value associated with the key `'id_900'`. 3. **Object in**: Using the `in` operator (`'id_900' in obj`) to check if the key exists in the object. **Script Preparation Code** The script preparation code creates a large array of key-value pairs, converts it into an `Array` and then an `Object`, and finally into a `Map`. This allows us to test each method on different data structures (array, object, and map). ```javascript var entries = new Array(1000).fill(0).map((_, i) => ['id_'+i, true]); var obj = Object.fromEntries(entries); var map = new Map(entries); ``` **Options Compared** The three options compared are: 1. **Lookup Map**: Using `has()` method on a `Map` object. * Pros: Fast and efficient for large maps. * Cons: May not work as expected for non-map objects, may be slower for small maps due to map overhead. 2. **Object dot**: Using property access syntax (`obj['id_900']`) to access the value associated with the key `'id_900'`. * Pros: Fast and efficient for objects. * Cons: May not work as expected if the key is not a string, may be slower for very large objects due to property lookup overhead. 3. **Object in**: Using the `in` operator (`'id_900' in obj`) to check if the key exists in the object. * Pros: Fast and efficient for objects. * Cons: May have performance issues with large objects, may not work as expected with non-object data structures. **Library Used** No external library is used in this benchmark. The `Map` class and the `Object.fromEntries()` method are built-in JavaScript features. **Special JS Feature/Syntax** The benchmark uses the following special syntax: * **Object from Entries**: The `Object.fromEntries()` method was introduced in ECMAScript 2015 (ES6). It allows creating an object from an array of key-value pairs. * **Map**: The `Map` class is a built-in JavaScript feature that allows creating a map data structure. **Other Considerations** When measuring performance, it's essential to consider factors like: * Cache locality: How does the method behave when executing multiple iterations with similar input? * Branch prediction: Does the method use conditional statements that can affect branch prediction? * Interpreter vs. compiler optimizations: Are there any differences in performance between interpreted and compiled code? **Alternatives** If you're looking for alternatives to this benchmark, consider: * **Array methods**: Using `indexOf()` or `includes()` on an array instead of a map. * **Object methods**: Using `in` operator with object literals instead of property access syntax. * **Native methods**: Using native methods like `get()` and `has()` on DOM elements instead of JavaScript objects. Keep in mind that the performance differences between these alternatives may be negligible or non-existent, depending on the specific use case and browser implementation.
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