Added logic to the bindgen::cargo_install_wasm_bindgen function to ch…

…eck if 'wasm-bindgen' already exists in the path. This might need some revisions to be Windows compatible.

src/bindgen.rs

@@ -1,9 +1,10 @@
 use PBAR;
 use console::style;
 use emoji;
-use std::process::Command;
+use std::{env, fs, process::Command};
 
 pub fn cargo_install_wasm_bindgen() {
+    if wasm_bindgen_installed() { return; }
     let step = format!(
         "{} {}Installing WASM-bindgen...",
         style("[6/7]").bold().dim(),
@@ -36,3 +37,16 @@ pub fn wasm_bindgen_build(path: &str, name: &str) {
         .unwrap_or_else(|e| panic!("{} failed to execute process: {}", emoji::ERROR, e));
     pb.finish();
 }
+
+fn wasm_bindgen_installed() -> bool {
+    if let Ok(path) = env::var("PATH") {
+        return path.split(":")
+            .map(|p: &str| -> bool {
+                let prog_str = format!("{}/{}", p, "wasm-bindgen");
+                fs::metadata(prog_str).is_ok()
+            })
+            .fold(false, |res, b| res || b);
+    } else {
+        return false;
+    }
+}