Debugging in VS Code Cookbook Recipe (#663)

* add in debugging in vscode

* change tips to new format

Author: sdras

src/.vuepress/config.js

@@ -3,7 +3,11 @@ const sidebar = {
     {
       title: 'Cookbook',
       collapsable: false,
-      children: ['/cookbook/', '/cookbook/editable-svg-icons']
+      children: [
+        '/cookbook/',
+        '/cookbook/editable-svg-icons',
+        '/cookbook/debugging-in-vscode'
+      ]
     }
   ],
   guide: [

src/.vuepress/public/images/breakpoint_hit.png

@@ -0,0 +1,124 @@
+# Debugging in VS Code
+
+Every application reaches a point where it's necessary to understand failures, small to large. In this recipe, we explore a few workflows for VS Code users who would like to debug their application in the browser.
+
+This recipe shows how to debug [Vue CLI](https://github.com/vuejs/vue-cli) applications in VS Code as they run in the browser.
+
+## Prerequisites
+
+Make sure you have VS Code and the browser of your choice installed, and the latest version of the corresponding Debugger extension installed and enabled:
+
+- [Debugger for Chrome](https://marketplace.visualstudio.com/items?itemName=msjsdiag.debugger-for-chrome)
+- [Debugger for Firefox](https://marketplace.visualstudio.com/items?itemName=hbenl.vscode-firefox-debug)
+
+Install and create a project with the [vue-cli](https://github.com/vuejs/vue-cli), following the instructions in the [Vue CLI Guide](https://cli.vuejs.org/). Change into the newly created application directory and open VS Code.
+
+### Displaying Source Code in the Browser
+
+Before you can debug your Vue components from VS Code, you need to update the generated Webpack config to build sourcemaps. We do this so that our debugger has a way to map the code within a compressed file back to its position in the original file. This ensures that you can debug an application even after your assets have been optimized by Webpack.
+
+If you use Vue CLI 2, set or update the `devtool` property inside `config/index.js`:
+
+```json
+devtool: 'source-map',
+```
+
+If you use Vue CLI 3, set or update the `devtool` property inside `vue.config.js`:
+
+```js
+module.exports = {
+  configureWebpack: {
+    devtool: 'source-map',
+  },
+}
+```
+
+### Launching the Application from VS Code
+
+::: info
+We're assuming the port to be `8080` here. If it's not the case (for instance, if `8080` has been taken and Vue CLI automatically picks another port for you), just modify the configuration accordingly.
+:::
+
+Click on the Debugging icon in the Activity Bar to bring up the Debug view, then click on the gear icon to configure a launch.json file, selecting **Chrome/Firefox: Launch** as the environment. Replace content of the generated launch.json with the corresponding configuration:
+
+![Add Chrome Configuration](/images/config_add.png)
+
+```json
+{
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "type": "chrome",
+      "request": "launch",
+      "name": "vuejs: chrome",
+      "url": "http://localhost:8080",
+      "webRoot": "${workspaceFolder}/src",
+      "breakOnLoad": true,
+      "sourceMapPathOverrides": {
+        "webpack:///src/*": "${webRoot}/*"
+      }
+    },
+    {
+      "type": "firefox",
+      "request": "launch",
+      "name": "vuejs: firefox",
+      "url": "http://localhost:8080",
+      "webRoot": "${workspaceFolder}/src",
+      "pathMappings": [{ "url": "webpack:///src/", "path": "${webRoot}/" }]
+    }
+  ]
+}
+```
+
+## Setting a Breakpoint
+
+1.  Set a breakpoint in **src/components/HelloWorld.vue** on `line 90` where the `data` function returns a string.
+
+![Breakpoint Renderer](/images/breakpoint_set.png)
+
+2.  Open your favorite terminal at the root folder and serve the app using Vue CLI:
+
+```
+npm run serve
+```
+
+3.  Go to the Debug view, select the **'vuejs: chrome/firefox'** configuration, then press F5 or click the green play button.
+
+4.  Your breakpoint should now be hit as a new browser instance opens `http://localhost:8080`.
+
+![Breakpoint Hit](/images/breakpoint_hit.png)
+
+## Alternative Patterns
+
+### Vue Devtools
+
+There are other methods of debugging, varying in complexity. The most popular and simple of which is to use the excellent Vue.js devtools [for Chrome](https://chrome.google.com/webstore/detail/vuejs-devtools/nhdogjmejiglipccpnnnanhbledajbpd) and [for Firefox](https://addons.mozilla.org/en-US/firefox/addon/vue-js-devtools/). Some of the benefits of working with the devtools are that they enable you to live-edit data properties and see the changes reflected immediately. The other major benefit is the ability to do time travel debugging for Vuex.
+
+![Devtools Timetravel Debugger](/images/devtools-timetravel.gif)
+
+Please note that if the page uses a production/minified build of Vue.js (such as the standard link from a CDN), devtools inspection is disabled by default so the Vue pane won't show up. If you switch to an unminified version, you may have to give the page a hard refresh to see them.
+
+### Simple Debugger Statement
+
+The example above has a great workflow. However, there is an alternative option where you can use the [native debugger statement](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/debugger) directly in your code. If you choose to work this way, it's important that you remember to remove the statements when you're done.
+
+```js
+<script>
+export default {
+  data() {
+    return {
+      message: ''
+    }
+  },
+  mounted() {
+    const hello = 'Hello World!'
+    debugger
+    this.message = hello
+  }
+};
+</script>
+```
+
+## Acknowledgements
+
+This recipe was based on a contribution from [Kenneth Auchenberg](https://twitter.com/auchenberg), [available here](https://github.com/Microsoft/VSCode-recipes/tree/master/vuejs-cli).