egui_web: Add simple fetch API and demostrate it in example_web

egui_web/src/fetch.rs

@@ -0,0 +1,53 @@
+use wasm_bindgen::prelude::*;
+
+pub struct Response {
+    pub url: String,
+    pub ok: bool,
+    pub status: u16,
+    pub status_text: String,
+
+    pub body: String,
+}
+
+/// NOTE: Ok(..) is returned on network error.
+/// Err is only for failure to use the fetch api.
+pub async fn get_text(url: &str) -> Result<Response, String> {
+    get_text_jsvalue(url)
+        .await
+        .map_err(|err| err.as_string().unwrap_or_default())
+}
+
+/// NOTE: Ok(..) is returned on network error.
+/// Err is only for failure to use the fetch api.
+async fn get_text_jsvalue(url: &str) -> Result<Response, JsValue> {
+    // https://rustwasm.github.io/wasm-bindgen/examples/fetch.html
+
+    use wasm_bindgen::JsCast;
+    use wasm_bindgen_futures::JsFuture;
+
+    let mut opts = web_sys::RequestInit::new();
+    opts.method("GET");
+    opts.mode(web_sys::RequestMode::Cors);
+
+    let request = web_sys::Request::new_with_str_and_init(&url, &opts)?;
+    request.headers().set("Accept", "*/*")?;
+
+    let window = web_sys::window().unwrap();
+    let resp_value = JsFuture::from(window.fetch_with_request(&request)).await?;
+
+    assert!(resp_value.is_instance_of::<web_sys::Response>());
+    let resp: web_sys::Response = resp_value.dyn_into().unwrap();
+
+    // TODO: headers
+    // TODO: support binary get
+    let body = JsFuture::from(resp.text()?).await?;
+    let body = body.as_string().unwrap_or_default();
+
+    Ok(Response {
+        status_text: resp.status_text(),
+        url: resp.url(),
+        ok: resp.ok(),
+        status: resp.status(),
+        body,
+    })
+}

egui_web/src/lib.rs

@@ -3,6 +3,7 @@
 #![warn(clippy::all)]
 
 pub mod backend;
+pub mod fetch;
 pub mod webgl;
 
 pub use backend::*;
@@ -14,10 +15,14 @@ use wasm_bindgen::prelude::*;
 // ----------------------------------------------------------------------------
 // Helpers to hide some of the verbosity of web_sys
 
-pub fn console_log(s: String) {
+pub fn console_log(s: impl Into<JsValue>) {
     web_sys::console::log_1(&s.into());
 }
 
+pub fn console_error(s: impl Into<JsValue>) {
+    web_sys::console::error_1(&s.into());
+}
+
 pub fn now_sec() -> f64 {
     web_sys::window()
         .expect("should have a Window")
@@ -182,6 +187,13 @@ pub fn set_clipboard_text(s: &str) {
     }
 }
 
+pub fn spawn_future<F>(future: F)
+where
+    F: std::future::Future<Output = ()> + 'static,
+{
+    wasm_bindgen_futures::spawn_local(future);
+}
+
 fn cursor_web_name(cursor: egui::CursorIcon) -> &'static str {
     use egui::CursorIcon::*;
     match cursor {