var obj = {};
var count = 10;
do {
obj["key" + count + ""] = "val" + count + "";
} while(count--);
var temp = [];
for(var key in obj) {
temp.push(obj[key]);
}
var objKey = [];
var keys = Object.keys(obj);
for(var i = 0, len = keys.length; i < len; i++) {
objKey.push(obj[keys[i]]);
}
var temp = [];
for(var key in obj) {
temp.push(obj[key]);
}
var objKey = [];
var keys = Object.keys(obj);
for(var i = 0, len = keys.length; i < len; i++) {
objKey.push(obj[keys[i]]);
}
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
for (key in obj) | |
Object.keys(obj) |
Test name | Executions per second |
---|---|
for (key in obj) | 851649.8 Ops/sec |
Object.keys(obj) | 694870.4 Ops/sec |
Let's break down the provided benchmark and its results.
Benchmark Overview
The benchmark measures the performance of two approaches for iterating over an object in JavaScript:
for...in
loop with the key
variable.Object.keys()
method.Script Preparation Code
The script preparation code creates a test object (obj
) and populates it with 10 properties using a loop. The temp
array is initialized to store the values from the object, while the objKey
array uses Object.keys()
to iterate over the object's keys.
Html Preparation Code
There is no HTML preparation code provided, which means that the benchmark only runs in the JavaScript environment and does not involve any DOM manipulation or rendering.
Library Usage
The Object.keys()
method is a built-in JavaScript function that returns an array of strings representing the property names of an object. This function uses the ECMAScript standard, specifically section 9.3.1, to implement its behavior.
Special JS Feature or Syntax
This benchmark does not use any special JavaScript features or syntax beyond what is commonly used in modern web development. However, it's worth noting that the for...in
loop with the key
variable uses an older style of iteration that can be slower than more modern approaches like Object.keys()
.
Pros and Cons of Approaches
in
.for...in
loop.Other Alternatives
There are other approaches for iterating over objects in JavaScript, such as:
forEach()
can be used to iterate over an object's properties using a callback function.In summary, the benchmark provides a simple and straightforward comparison between two common approaches for iterating over objects in JavaScript. The results should help developers understand the relative performance characteristics of these approaches and choose the most suitable one depending on their specific use case and requirements.