yew/build-a-sample-app.md at b9863c1f5c537fc35f727684bcded8ce91ef4aba

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id	title
sample-app	Build a sample app

First create a new Rust library **important:** create a _library_, not a _binary_ by passing the `--lib` flag:

cargo new --lib yew-app && cd yew-app

Add yew and wasm-bindgen to your dependencies refer [here](https://docs.rs/yew) for the latest version

[package]
name = "yew-app"
version = "0.1.0"
authors = ["Yew App Developer <name@example.com>"]
edition = "2018"

[lib]
crate-type = ["cdylib", "rlib"]

[dependencies]
yew = "0.17"
wasm-bindgen = "0.2"

Copy the following template into your src/lib.rs file:

use wasm_bindgen::prelude::*;
use yew::prelude::*;

struct Model {
    link: ComponentLink<Self>,
    value: i64,
}

enum Msg {
    AddOne,
}

impl Component for Model {
    type Message = Msg;
    type Properties = ();
    fn create(_: Self::Properties, link: ComponentLink<Self>) -> Self {
        Self {
            link,
            value: 0,
        }
    }

    fn update(&mut self, msg: Self::Message) -> ShouldRender {
        match msg {
            Msg::AddOne => self.value += 1
        }
        true
    }

    fn change(&mut self, _props: Self::Properties) -> ShouldRender {
        // Should only return "true" if new properties are different to
        // previously received properties.
        // This component has no properties so we will always return "false".
        false
    }

    fn view(&self) -> Html {
        html! {
            <div>
                <button onclick=self.link.callback(|_| Msg::AddOne)>{ "+1" }</button>
                <p>{ self.value }</p>
            </div>
        }
    }
}

#[wasm_bindgen(start)]
pub fn run_app() {
    App::<Model>::new().mount_to_body();
}

This template sets up your root Component, called Model which shows a button that updates itself when you click it. Take special note of App::<Model>::new().mount_to_body() inside main() which starts your app and mounts it to the page's <body> tag. If you would like to start your application with any dynamic properties, you can instead use App::<Model>::new().mount_to_body_with_props(..).

Finally, add an index.html file into a new folder named static in your app.

mkdir static

<!doctype html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <title>Yew Sample App</title>
        <script type="module">
            import init from "./wasm.js"
            init()
        </script>
    </head>
    <body></body>
</html>

Run your App!

Using wasm-pack is the preferred way to get up and running. If you haven't already, install wasm-pack with cargo install wasm-pack and then build and start a development server by running:

wasm-pack build --target web --out-name wasm --out-dir ./static

wasm-pack generates a bundle in the ./static directory with your app's compiled WebAssembly along with a JavaScript wrapper which will load your application's WebAssembly binary and run it.

Then, use your favorite web server to server the files under ./static. For example:

cargo +nightly install miniserve
miniserve ./static --index index.html

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Run your App!

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