let x = 0;
for (var i=0; i < 1000; i++)
{
x += 2 + i;
}
let x = 0;
for (var i=0; i < 1000; i++)
{
x = x + 2 + i;
}
var x = 0;
for (var i=0; i < 1000; i++)
{
x += 2 + i;
}
var x = 0;
for (var i=0; i < 1000; i++)
{
x = x + 2 + i;
}
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
Plus equals | |
Plus | |
Var plus equals | |
var plus |
Test name | Executions per second |
---|---|
Plus equals | 170950.9 Ops/sec |
Plus | 375328.5 Ops/sec |
Var plus equals | 468591.6 Ops/sec |
var plus | 374921.3 Ops/sec |
Measuring the performance of different JavaScript expressions is a complex task, and I'll break it down into manageable parts.
Benchmark Overview
The provided benchmark measures the performance of four different JavaScript expressions that perform addition operations on a variable x
. The expressions are:
Plus equals
: x += 2 + i
Plus
: x = x + 2 + i
Var plus equals
: var x = 0; x += 2 + i
Var plus
: var x = 0; x = x + 2 + i
Options Compared
The benchmark compares the performance of these four expressions on a loop that iterates from 0 to 999.
Pros and Cons of Each Approach
x += 2 + i
):x
before use.x = x + 2 + i
):x
, which may introduce overhead.var x = 0; x += 2 + i
):x
before use, which may incur additional overhead.var x = 0; x = x + 2 + i
):x
, which may introduce overhead.Library and Special JS Features
None of the expressions use any external libraries or special JavaScript features. The focus is on comparing the performance of basic arithmetic operations in different contexts.
Device-Specific Considerations
The benchmark results are reported for a specific device, Chrome Mobile 52 running on Android 6.0.1. It's essential to note that device-specific factors, such as processor architecture and operating system version, can significantly impact performance.
Other Alternatives
If you're interested in exploring alternative approaches or optimizations, consider the following:
const
instead of var
for declaring variables, which can help with optimization.let
instead of var
if you need to reassign the variable within a block scope.template literals
(${expression}
) instead of string concatenation or interpolation for more readable and efficient code.Function
constructors or arrow functions for concise and expressive code.Keep in mind that these alternatives may not necessarily improve performance but can make your code more maintainable, readable, and efficient.