Kelvin Wangonya

Posted on Oct 4, 2018

Dart String to Int How you turn a string into a number (or vice versa) with Dart

#dart #learning #beginners #webdev

When you're so used to one language and you're trying to learn a new one, its likely that you'll find yourself always looking back to what you already know to find out if the new language matches up. I know I do. If I find similarities, I'm happy 🙂. If I find more features, I'm excited 😄. If the new language is lacking, I'm like, how come something so important (however trivial the thing may be) is missing 🤨 I can't work with this.

Say I needed to turn a string into a number with Javascript, there's a number of ways I could do it:

Dart has almost similar functions to achieve the same results.

Turning a string into a number (or vice versa) with Dart

You can try out the code snippets on dartpad

String to int

// String -> int
main () {
    var one = int.parse('1');
    print(one == 1); // prints true
}

String to double

// String -> double
main () {
    var onePointOne = double.parse('1.1');
    print(onePointOne == 1.1); // prints true
}

int to String

// int -> String
main () {
    String oneAsString = 1.toString();
    print(oneAsString == '1'); // prints true
}

double to String

// double -> String
main () {
    String piAsString = 3.14159.toStringAsFixed(2);
    print(piAsString == '3.14'); // prints true
}

I've been wanting to take up mobile app development with flutter so I thought I'd get comfortable with dart first before diving into flutter. So far, I'm happy. Coming from Javascript, Dart is easy to pick up, and fun to learn.

Top comments (16)

Jermaine • Oct 4 '18

You just made my day bro! Happy to see another person covering raw dart concepts. Keep it up!

Kelvin Wangonya • Oct 4 '18

Hey Jermaine. Interesting that I did a search for Dart posts on Dev.to before posting this and I only saw your posts 😅 Like almost all the search results were yours. I think Dart is really great and it isn't getting the attention it deserves. Thanks for stopping by!

Ben Halpern • Oct 4 '18

When I glanced at this title I figured it would be one of Jermaine's. 😄

Jermaine • Oct 5 '18

😄

Adam Crockett 🌀 • Oct 4 '18 • Edited

What's it like to work with Dart as JavaScript?

Kelvin Wangonya • Oct 4 '18

Hi Adam. To be honest, I just started out with Dart today so I can't give a very comprehensive answer. I think Jermaine's answer covers it though 🙂

Jermaine • Oct 4 '18

For me, working with Dart is a lot linear, since the necessary tooling are provided by the Dart team. Because it's a typed language, being productive in little time is easier, especially when combined with the range of utilities that come as part of the SDK. I can also use JavaScript libraries in my Dart web apps.

Adam Crockett 🌀 • Oct 5 '18

Thanks for the reply, so I work with Typescript 99% of the time, from experience, I need to get a definition file in order the use them in TS in a meaningful way. How does this compare?

Is there a reason to consider Dart over TS? What is the coverage for the JavaScript library ecosystem in pub, have you had to make decisions based on what is in the pub repo.

Sorry to go off topic here @Kinyanjui.

Jermaine • Oct 6 '18

from experience, I need to get a definition file in order the use them in TS in a meaningful way. How does this compare?

Similarly, a definition file is needed to use JS libraries in Dart. You can create one yourself with little effort. Furthermore, you can use this tool developed by the Dart team to convert TS definitions to Dart.

Is there a reason to consider Dart over TS?

Dart and TypeScript are both attempts to address the shortcomings of native JavaScript. I would consider Dart especially in the area of mobile app development with Flutter. Dart can be compiled to native ARM code, which is good for performance.

The pull with Dart here is the tooling and utilities that come with it, not just the language. I find with TypeScript that one can fall into the trap of writing code that looks too much like C# than JS, which tells me Dart may have been the right approach, implementing conventions that programmers use and love without being bound to the constraints of JavaScript.

What is the coverage for the JavaScript library ecosystem in pub, have you had to make decisions based on what is in the pub repo.

Haven't got any numbers on that one I'm afraid. There are Dart packages that act as wrappers over JS libs, using the js interop package I covered in my tutorial. I found examples like Google Maps and ChartJS, although you can make your own using the tools provided.

Thanks for your questions. I'm up for suggestions on any future topics you wish for me to cover. Message me on Twitter 🐦.

Kelvin Wangonya • Oct 4 '18

I didn't know you can use Javascript libraries in Dart. That's really cool.

Adam Crockett 🌀 • Oct 5 '18

Before Dart as it is today, Dart was going to be a replacement for JavaScript (in Googles mind), There is a Dartium version of chrome that ran Dart 1. The decision was made to rebirth Dart into what it is today, but I see that the JavaScript compiler exists. So the idea is not dead, just different.

Jermaine • Oct 6 '18

The dart2js compiler to JavaScript is necessary if we need to develop apps that run on the web. An aim with Dart 2 was to improve the tooling geared towards clientside development. They wrote about this on their Medium blog.