Convert String to Number: Which method is better and why?

Question

I'm not sure if there are other methods, but I've come across these three.

Quick example:
parseInt("10.4") == 10 // true
parseFloat("10.4") == 10.4 // true
Number("10.4") == parseFloat("10.4") // true

My question is between parseFloat() and Number().
Since they both do the same thing, which is better to use?

I am aware that parseFloat is a built-in function of Number. So if Number() is called, is it just routing everything through parseFloat function? Is it therefore slightly better performance-wise to just call the function directly?

Answer 1

They don't "both do the same thing"...

var text_number = "10.4px";
var float = parseFloat(text_number); // 10.4
var num = Number(text_number); // NaN

text_number = "";
float = parseFloat(text_number); // NaN
num = Number(text_number); // 0

However, '+' operator "do the same thing" as Number():

num = + text_number; // 0
text_number = "42";
num = + text_number; // 42

Answer 2

That's not issues, that's behaviours ^^
parseFloat() and parseInt() are intended to parse number from string, while Number() is a constructor and is intended to convert any value type to numeric...

Answer 3

Interesting! Thanks @visph!
I need to play around with that a bit more. Thanks a lot for your insight.

I see a lot of parseFloat() used most of the time. But it's possible to throw it into an error. I see even in your example that parseFloat("") will result in NaN. Of course more conditions could be given to prevent code from breaking.

Anyway- so far it seems like all methods have their own issues.

Answer 4

@visph...
Thanks for your time!

Helps to know the ins-and-outs of methods etc. to know which one to use and why.