add ClientBuilder.default_headers() for wasm32 target (#1084)

examples/form.rs

@@ -1,9 +1,20 @@
+// Short example of a POST request with form data.
+//
+#[cfg(not(target_arch = "wasm32"))]
 #[tokio::main]
 async fn main() {
-    reqwest::Client::new()
+    let response = reqwest::Client::new()
         .post("http://www.baidu.com")
         .form(&[("one", "1")])
         .send()
         .await
-        .unwrap();
+        .expect("send");
+    println!("Response status {}", response.status());
 }
+
+// The [cfg(not(target_arch = "wasm32"))] above prevent building the tokio::main function
+// for wasm32 target, because tokio isn't compatible with wasm32.
+// If you aren't building for wasm32, you don't need that line.
+// The two lines below avoid the "'main' function not found" error when building for wasm32 target.
+#[cfg(target_arch = "wasm32")]
+fn main() {}

examples/simple.rs

@@ -3,6 +3,7 @@
 // This is using the `tokio` runtime. You'll need the following dependency:
 //
 // `tokio = { version = "0.2", features = ["macros"] }`
+#[cfg(not(target_arch = "wasm32"))]
 #[tokio::main]
 async fn main() -> Result<(), reqwest::Error> {
     let res = reqwest::get("https://hyper.rs").await?;
@@ -15,3 +16,10 @@ async fn main() -> Result<(), reqwest::Error> {
 
     Ok(())
 }
+
+// The [cfg(not(target_arch = "wasm32"))] above prevent building the tokio::main function
+// for wasm32 target, because tokio isn't compatible with wasm32.
+// If you aren't building for wasm32, you don't need that line.
+// The two lines below avoid the "'main' function not found" error when building for wasm32 target.
+#[cfg(target_arch = "wasm32")]
+fn main() {}