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ObjKeys vs ForIn
(version: 0)
Object.keys vs. For..In
Comparing performance of:
ObjKeys vs ForIn
Created:
6 years ago
by:
Guest
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Script Preparation code:
var jsonObj = { prop1: "abc", prop2: "def", prop3: "ghi", prop4: "jkl", prop5: "mno", prop6: "pqr", prop7: "stu", prop8: "vwx", prop9: "yz", prop10: "abc", prop11: "abc", prop12: "def", prop13: "ghi", prop14: "jkl", prop15: "mno", prop16: "pqr", prop17: "stu", prop18: "vwx", prop19: "yz", prop20: "yz", prop21: "abc", prop22: "def", prop23: "ghi", prop24: "jkl", prop25: "mno", prop26: "pqr", prop27: "stu", prop28: "vwx", prop29: "yz", prop31: "abc", prop32: "def", prop33: "ghi", prop34: "jkl", prop35: "mno", prop36: "pqr", prop37: "stu", prop38: "vwx", prop39: "yz", prop41: "abc", prop42: "def", prop43: "ghi", prop44: "jkl", prop45: "mno", prop46: "pqr", prop47: "stu", prop48: "vwx", prop49: "yz", prop51: "abc", prop52: "def", prop53: "ghi", prop54: "jkl", prop55: "mno", prop56: "pqr", prop57: "stu", prop58: "vwx", prop59: "yz", prop61: "abc", prop62: "def", prop63: "ghi", prop64: "jkl", prop65: "mno", prop66: "pqr", prop67: "stu", prop68: "vwx", prop69: "yz" }
Tests:
ObjKeys
var result = ""; Object.keys(jsonObj).forEach(function(key) { result = result + jsonObj[key]; });
ForIn
var result = ""; for (key in jsonObj) { if (jsonObj.hasOwnProperty(key)) { result = result + jsonObj[key]; } }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
ObjKeys
ForIn
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**Benchmark Explanation** The provided JSON represents two test cases, `ObjKeys` and `ForIn`, which compare the performance of two approaches to iterate over an object's properties in JavaScript. **Approaches Compared:** 1. **Object.keys()**: This method returns an array of a given object's own enumerable property names. 2. **For...In Loop**: This loop iterates over the properties of an object, including inherited ones, using the `in` keyword. **Pros and Cons:** * **Object.keys()**: + Pros: - More concise and readable code - Less prone to errors due to automatic exclusion of non-enumerable properties + Cons: - May be slower for very large objects, since it needs to create an array of property names - Does not guarantee iteration order (properties are returned in the order they were added to the object) * **For...In Loop**: + Pros: - Can access non-enumerable properties using `jsonObj.hasOwnProperty(key)` - Guarantees iteration order (properties are visited in the order they appear in the object's prototype chain) + Cons: - More verbose and error-prone code - Can be slower for large objects, since it needs to iterate over all inherited properties **Library/Functionality Used:** * None explicitly mentioned. However, it's assumed that `jsonObj` is an object created using the provided JSON data. **Special JS Feature/Syntax:** * **String concatenation with addition (`+`)**: This approach uses the `+=` operator to concatenate strings, which may have performance implications. * **`forEach()` method**: This approach uses the `forEach()` method to iterate over an array. While this is a standard JavaScript feature, it's worth noting that some older browsers may not support it. **Alternative Approaches:** 1. **Using `for...of` loop with `entries()` method**: This would be another way to iterate over an object's properties using the `for...of` loop syntax. 2. **Using a custom iterator function**: This would allow for more fine-grained control over iteration and optimization. 3. **Using a different data structure (e.g., array)**: Depending on the specific use case, using an array of objects or another data structure might offer performance benefits. In summary, this benchmark compares two common approaches to iterate over object properties in JavaScript, highlighting their trade-offs in terms of conciseness, readability, and performance.
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