How to enable debugging mode in VSCode? Brief analysis of three methods

This article will introduce the necessity of trial mode to everyone, and talk about the three ways to enable debugging mode in VSCode. I hope it will be helpful to everyone!

In the process of code writing or maintenance (bug), for simple values ​​or problems, we can use Console can be used to solve the problem. Some people even think that console is a good method and a silver bullet that can solve all problems. I don’t think it is. For those who want to clarify the execution logic of the code, there is also the option of checking complex types. (Reference type) value, you still have to use debug mode (debugger). https://juejin.cn/post/7024890041948176398#heading-1

debugger is a statement in js, run here One line, if the program is in debugging mode, there will be a breakpoint, that is, it will stop at this line, then we can see the context at this time, including the values ​​of the most important variables, and the call stack. And it also supports our single Debugging step by step, or debugging block by block.

Usually debugging is more in the browser. In the browser, you only need to open the console, turn on the debugging mode, and then encounter# The ##debugger statement, or a custom breakpoint, will stop the program and enter debug mode.

This article will mainly discuss how to enable debugging mode in

vscode, because I am going to write a vscode plug-in (stay tuned), debugging vscode is inevitable, and the simple debugging before will definitely not meet my needs, so let’s learn about the debugging mode of vscode.

This article will not write about debugging skills, but will write about,

vscodeHow to enable debuggingjs. Here is vscodeofficial documentation

Rediscuss the necessity of debugging mode

If you only need to see a simple value, then you can use

console, because the debugging mode is turned on The cost is relatively large.

In the browser, because the object is a reference type and the browser will not directly fold the object, so if

consoleafter After modifying the object, go to the console to see it. What you get will be the modified object

It will not be automatically folded after printing

When I fold it manually, the browser reads the value again and it has become the modified value

This kind of problem occurs because of the object, so if we convert it to a string and then print it, we won't have this problem. However, it doesn't look good. Here is just an example. In some cases, you still need to use debugging mode.

Enable debugging mode in

vscode

Debug in

vscodejs,ts Code, there are three ways

• When running

  node in the vscode terminal, it will be automatically attached, See 3.1 .

##Directly use the
• debug

  terminal provided by vscode, see 3.2

Use the configuration file,
• See 3.3

1 Auto Attach

In When running

node

in the terminal of vscode, it will automatically determine whether to start the debug mode based on different options.

There are 4 options in total, and there are three ways to switch options

1.1 Ways to switch options

No matter which setting method is used, change After knowing the setting method, it is best to restart

vscode

to make it take better effect

By setting

##By modifying the configuration file

Open the configuration filesettings.jsonAfter the file

// 修改或添加
{
  "debug.javascript.autoAttachFilter": "onlyWithFlag"
}

By command (recommended)

Use Ctrl Shift P to call up the command (macor find it yourself if you have modified the shortcut keys),

Enter attach to find it. After selecting, you can see these four options, and then select the option again to switch to the option you want

1.2 The meaning of each option

The documentation on the official website has not been updated, and the default option is no longersmart , changed to disabled

option	meaning
Always (always)	Always start in debug mode
Intelligent(smart)	Only the specified file will enter the debug mode
Only with the flag (onlyWithFlag )	With --inspect or inspect-brk parameters, start in debug mode
Disabled(disabled)	Never start in debug mode

Smart(smart) is the file path that specifies whether to enable debug mode through the debug.javascript.autoAttachSmartPattern configuration item. The default value is ["${ workspaceFolder}/**","!**/node_modules/**","**/$KNOWN_TOOLS$/**"]

##If started

disable( disabled) mode, then node --inspect will not enter debug mode, and can only be entered by opening a debug terminal in the following way debug mode, hey~ vscode is also a scam, I don’t know when the default mode was changed to disabled, so I remember one time I used node --inspect failed to enter the debug mode, which was quite strange. Now I understand what happened.

2 JavaScript Debug Terminal(debug Terminal)

Directly start a terminal in

debug mode, and node started in it will enter debug mode.

Through the above method (

Auto Attach), all terminals started in vscode are controlled. This only controls the one started by it. Terminal.

3 Launch Configuration

#This is the highlight, and I am the main one Want to know more about this

Startup configuration is a way to set how to start the

debug mode in the form of a configuration file. It provides more configuration to meet the needs of running and debugging. Complex application

3.1 Properties of launch configuration

This configuration file is located in

.vscode/launch.json in the current workspace directory , you can create one manually, or quickly create one through vscode

and then select

nodeThat’s it

Required attributes

##Required attributes, the most modified ones should be

name

, the other two are in node and generally will not be modified.

Attribute nametypenode => pwa-node##requestThe request type of launch mode has only two values ​​: start, nameThe name of this startup configuration is used by the user to distinguish Customized, just understand it yourself, for your own use

request

我们常用的是 launch , 所以这里只是讨论了 launch 的使用.

对于 launch 和 attach 的区别, 可以看 B 站上这个大佬的视频, 讲解地很好. 程序员阿汤 => 介绍 launch.json

name

name的含义是: 一个launch.json中可以配置多个启动配置, 所以需要给每个启动配置起个名字, 用于区分

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "node调试",
      "port": 9229,
      "request": "attach",
      "skipFiles": ["<node_internals>/**"],
      "type": "pwa-node"
    },
    {
      "type": "pwa-chrome",
      "request": "attach",
      "name": "chrome调试",
      "url": "http://localhost:8080",
      "webRoot": "${workspaceFolder}"
    }
  ]
}

选中某一个, 然后可以使用快捷键f5, 快速启动, 或者点击运行图标

launch和attach都支持的属性

Meaning	Attribute value example
Debugger type, can also be considered as debugging language		, chrome => pwa-chrome
debug	launch	attach: attach

属性	含义
outFiles	指定Source maps文件所在路径
resolveSourceMapLocations	也是指定与Source maps相关的路径
timeout	附加的超时时间, 超时就放弃
stopOnEntry	项目启动起来, 立即debugger一下, 就是相当于在代码的第一行加了一个debugger
localRoot	这个是用来远程调试用的, 我就先不了解它了...
remoteRoot	这个是用来远程调试用的, 我就先不了解它了...
smartStep	自动跳过没有映射到的源文件
skipFiles	指定单步跳过的文件, 就是debugger不跟进去看的源代码
trace	开启会将一些调试输出保存到vscode指定的文件中

skipFiles

(这个挺有用的, 有些代码不想跟进去看, 但是经常点快了, 就进去了..., 可以把这些文件排除掉, <node_internals>/**/*.js</node_internals>配置上这个, 可以跳过node核心模块的代码.)

trace

开启trace后

launch支持的属性

属性	含义
program	启动项目的入口文件地址(就是要执行的js的路径)
args	相当于命令行参数(下面有详解)
cwd	指定程序启动的路径(下面有详解)
runtimeExecutable	指定可执行程序的启动路径(下面有详解)
runtimeArgs	给可执行程序的参数(下面有详解)
env	指定环境变量(下面有详解)

args

"args": ["aaa", "bbb"] :在命令行传递参数的方式, 在node中可以通过process.argv拿到

cwd

"cwd": "${workspaceFolder}/demo", 配置这个路径, 在node中, 相当于指定了process.cwd()的路径

runtimeExecutable

这个可以指定启动的程序名, 比如使用nodemon启动, 或者指定路径, 比如你有 3 个版本的 node 想启动调试看看各个版本的差异, 就不需要切换全局的 node 版本, 只需要设置多个配置项就行啦. 这样很方便的.

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "v10 版本启动",
      "program": "${workspaceFolder}/demo.js",
      "request": "launch",
      "type": "pwa-node",
      "runtimeExecutable": "C:\\Program Files\\nodejsv10\\node.js" // 这里是 v10 版本的node路径
    },
    {
      "name": "v11 版本启动",
      "program": "${workspaceFolder}/demo.js",
      "request": "launch",
      "type": "pwa-node",
      "runtimeExecutable": "C:\\Program Files\\nodejsv11\\node.js" // 这里是 v11 版本的node路径
    },
    {
      "name": "v12 版本启动",
      "program": "${workspaceFolder}/demo.js",
      "request": "launch",
      "type": "pwa-node",
      "runtimeExecutable": "C:\\Program Files\\nodejsv12\\node.js" // 这里是 v12 版本的node路径
    }
  ]
}

runtimeArgs

这个里面写的参数会紧跟在可执行程序后面, 在node程序中, node会将它后面的第一个参数视为它要执行的文件的路径, 所以需要有所调整.

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "v10 版本启动",
      "program": "${workspaceFolder}/demo.js", // 这个现在已经不是 node 的执行文件地址了, 它只是一个参数了
      "request": "launch",
      "type": "pwa-node",
      "args": ["args1", "args2"],
      "runtimeArgs": ["${workspaceFolder}/demo.js", "runtimeArgs2"] // 因为它紧跟在 可执行程序后面, 所以它的第一个参数需要设置为它要执行的文件的地址
      // 如果它是 --experimental-modules 类型参数就没事了, 因为node会把它解析成参数, 这个参数的含义是 启动 es 模块支持. 接下来我会写一篇 js 的模块化的文章, 敬请期待哈
    }
  ]
}
// 启动的命令行是
// C:\Program Files\nodejs\node.exe E:\font-end/demo.js runtimeArgs2 .\demo.js args1 args2

这个参数在弄成 npm 启动项目的时候, 比较有用

env

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "v10 版本启动",
      "program": "${workspaceFolder}/demo.js",
      "request": "launch",
      "type": "pwa-node",
      "env": {
        "NODE_ENV": "prod"
      }
    }
  ]
}

attach支持的属性

我们常用的是 launch 方式启动, 就先不了解 attach 的方式启动了.

总结

对于如何在vscode中启动debug模式, 应该是比较清楚的了

在vscode中, 一共有三种方式启动debug调试, 分别是

• 自动附加(影响全局的终端), 如果对自己电脑性能有自信, 设置为always. 命令行运行进入debug模式.

• 强制开启(只影响这一个终端), 如果不方便配置开启全局的自动debug, 使用这种方式进入debug, 也是比较放便的, 就是重新开启这个debug终端之后, 需要cd到需要运行的js文件目录, 比较麻烦. 命令行运行进入debug模式.

• 配置开启(功能强大, 适合调试复杂应用),配置好.vscode/launch.json后, f5启动进入debug模式

// 比较完整一个 launch.json 配置
{
  // 使用 IntelliSense 了解相关属性。
  // 悬停以查看现有属性的描述。
  // 欲了解更多信息，请访问: https://go.microsoft.com/fwlink/?linkid=830387
  "version": "0.2.0",
  "configurations": [
    {
      "name": "v10 版本启动", // 配置名称
      "program": "${workspaceFolder}/demo.js", // 项目启动入口文件
      "request": "launch", // `debug`模式的请求方式
      "stopOnEntry": true, // 项目启动, 立即`debugger`一下
      "type": "pwa-node", // 调试器类型
      "env": {
        // 环境变量
        "NODE_ENV": "prod"
      },
      "args": ["aaaa"], // 启动命令时跟在 program 后的参数
      "skipFiles": [
        // 指定单步调试不进去的文件
        "<node_internals>/**" // node 的核心库, 比如`require`
      ],
      "cwd": "${workspaceFolder}", // 指定可执行程序的启动路径, process.cwd(),
      "runtimeExecutable": "nodemon", // 指定可执行程序名称, 或者路径, 在这里 type 为 pwa-node 默认值是 node
      "runtimeArgs": ["--experimental-modules"] // 启动命令时, 跟在 runtimeExecutable 后的参数
    }
  ]
}

最后

这里已经有三个坑了, 模块化,调试技巧, vscode插件开发, 我目前更想先写一个vscode插件,敬请期待.

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