var strB = "42.034";
var res = +strB;
var res = parseInt(strB);
var res = Number(strB);
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
plus | |
parseInt | |
Number |
Test name | Executions per second |
---|---|
plus | 8870430.0 Ops/sec |
parseInt | 5648142.0 Ops/sec |
Number | 5085881.5 Ops/sec |
I'd be happy to help you understand the benchmark.
What is being tested?
The provided JSON represents a JavaScript microbenchmark test case that compares three different ways to convert a string to a number: parseInt
, Number
, and the unary +
operator (which is equivalent to Math.floor
or Number.parseInt(str, 10)
).
In this specific benchmark, the input string is "42.034"
. The goal is to determine which method produces the fastest execution time.
Options compared:
The three options being compared are:
+
operator (plus
): This uses the unary +
operator to convert the string to a number. It's equivalent to using Math.floor
or Number.parseInt(str, 10)
.parseInt
: This uses the built-in parseInt
function to convert the string to an integer. The second argument (10 in this case) specifies the radix (base) of the input string.Number
: This uses the built-in Number
function to convert the string to a number.Pros and Cons:
+
operator (plus
):"42.034"
).parseInt
:+
operator, as it can handle decimal points and non-numeric characters.Number
:parseInt
, but with fewer function calls (one instead of two).Other considerations:
In JavaScript, when converting a string to a number, the engine will try to parse the string as an integer if possible. If the string contains a decimal point, it will be parsed as a float instead. This means that parseInt
and Number
may produce different results for the input string "42.034"
, depending on how you expect the result to be treated (as an integer or a floating-point number).
Library used:
None.
Special JS feature or syntax:
No special features or syntax are mentioned in this benchmark.
Now, let's look at some alternative approaches:
parseFloat
: This function can also be used to convert a string to a float. However, it would not be a good candidate for this benchmark since it's slower than the unary +
operator and Number
.Keep in mind that this benchmark is focused on comparing different ways to perform simple string-to-number conversions. The goal is to determine which method produces the fastest execution time for a specific input scenario.