クロスプラットフォームなアプリ作成ツール「Electron」で遊ぶ　その３：自前のJSファイルはいつ読まれるか

考えてみれば当たり前なのですが……
起動の順番としては
1. main.js
2. index.html
3. index.htmlで読み出されたjs
という順で処理されます。
というわけで……addEventListner等々、自前のスクリプトはmain.jsに書いても無駄です。

実際のところ

main.js

'use strict';
const electron = require('electron');
const app = electron.app;  // Module to control application life.
const BrowserWindow = electron.BrowserWindow;  // Module to create native browser window.

// Report crashes to our server.
electron.crashReporter.start();

// Keep a global reference of the window object, if you don't, the window will
// be closed automatically when the JavaScript object is garbage collected.
let mainWindow;

// Quit when all windows are closed.
app.on('window-all-closed', function() {
  // On OS X it is common for applications and their menu bar
  // to stay active until the user quits explicitly with Cmd + Q
  if (process.platform != 'darwin') {
    app.quit();
  }
});

// This method will be called when Electron has finished
// initialization and is ready to create browser windows.
app.on('ready', function() {
  // Create the browser window.
    mainWindow = new BrowserWindow({width: 640, height: 480});
    mainWindow.loadURL(`file://${__dirname}/index.html`);
		       
  // Emitted when the window is closed.
  mainWindow.on('closed', function() {
    // Dereference the window object, usually you would store windows
    // in an array if your app supports multi windows, this is the time
    // when you should delete the corresponding element.
    mainWindow = null;
  });
});

index.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Hello World!</title>
  </head>
  <body>
    <script src="./app.js"></script>
    <webview id="foo" src="https://duckduckgo.com/" style="display:inline-block; width:320px; height:240px">...loading</webview>
<p>str</p>
    <form>
      <input type="button" id="btn1" value="CLICKHERE">
      <input type="button" value="<=" onClick="webview.goBack();">
    </form>
  </body>
</html>

app.js

onload = function(){
   alert("done");
};

onload = function() {
    var btn1 = document.getElementById("btn1");
    btn1.onclick = function(){
	document.bgColor='#000000';
    }
    
    var webview = document.getElementById("foo");
    var indicator = document.querySelector(".indicator");
    
    var loadstart = function() {
	indicator.innerText = "loading...";
    }
    
    var loadstop = function() {
	indicator.innerText = "";
    }
    
    webview.addEventListener("did-start-loading", loadstart);
    webview.addEventListener("did-stop-loading", loadstop);
};