SpaceX上的Javascript 这下面试造火箭没准真就去造火箭了

在上个月SpaceX 成功发射了载人火箭Dragon 2，其中的飞行界面就是由Chromium 和JavaScript进行构建的，当然只有图形界面是，系统的其他部分还是由c++来完成的。

Also, only the actual graphical display application uses Chromium/JS. The rest of the system is all C++. The display code has 100% test coverage, down to validation of graphical output (for example if you have a progress bar and you set it to X% the tests verify that it is actually drawn correctly).

不知道会不会出现氧气剩余 NaN%，着陆地点undefined

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火箭的操作界面估计是不会开源了，但是SpaceX-API 倒是在GitHub上开源了。

继阿波罗登月的代码之后又参与了SpaceX-API 的review，以后面试问我参与过什么项目就可以说参与过阿波罗登月计划和SpaceX 载人航天计划的code review。感觉准备个PPT可以去融资了。

什么是SpaceX-API

SpaceX-API 是一个用于火箭、核心舱、太空舱、发射台和发射数据的开源 REST API。

接口文档展示了所提供的 API 接口，还包括多种语言的接口调用。

比如dragons的信息：

[
  {
    "id": "dragon1",
    "name": "Dragon 1",
    "type": "capsule",
    "active": true,
    "crew_capacity": 0,
    "sidewall_angle_deg": 15,
    "orbit_duration_yr": 2,
    "dry_mass_kg": 4200,
    "dry_mass_lb": 9300,
    "first_flight": "2010-12-8",
    "heat_shield": {
      "material": "PICA-X",
      "size_meters": 3.6,
      "temp_degrees": 3000,
      "dev_partner": "NASA"
    },
    "thrusters": [
      {
        "type": "Draco",
        "amount": 18,
        "pods": 4,
        "fuel_1": "nitrogen tetroxide",
        "fuel_2": "monomethylhydrazine",
        "thrust": {
          "kN": 0.4,
          "lbf": 90
        }
      }
    ],
    "launch_payload_mass": {
      "kg": 6000,
      "lb": 13228
    },
    "launch_payload_vol": {
      "cubic_meters": 25,
      "cubic_feet": 883
    },
    "return_payload_mass": {
      "kg": 3000,
      "lb": 6614
    },
    "return_payload_vol": {
      "cubic_meters": 11,
      "cubic_feet": 388
    },
    "pressurized_capsule": {
      "payload_volume": {
        "cubic_meters": 11,
        "cubic_feet": 388
      }
    },
    "trunk": {
      "trunk_volume": {
        "cubic_meters": 14,
        "cubic_feet": 494
      },
      "cargo": {
        "solar_array": 2,
        "unpressurized_cargo": true
      }
    },
    "height_w_trunk": {
      "meters": 7.2,
      "feet": 23.6
    },
    "diameter": {
      "meters": 3.7,
      "feet": 12
    },
    "wikipedia": "https://en.wikipedia.org/wiki/SpaceX_Dragon",
    "description": "Dragon is a reusable spacecraft developed by SpaceX, an American private space transportation company based in Hawthorne, California. Dragon is launched into space by the SpaceX Falcon 9 two-stage-to-orbit launch vehicle. The Dragon spacecraft was originally designed for human travel, but so far has only been used to deliver cargo to the International Space Station (ISS)."
  },
  {
    "id": "dragon2",
    "name": "Dragon 2",
    "type": "capsule",
    "active": false,
    "crew_capacity": 7,
    "sidewall_angle_deg": 15,
    "orbit_duration_yr": 2,
    "dry_mass_kg": 6350,
    "dry_mass_lb": 14000,
    "first_flight": null,
    "heat_shield": {
      "material": "PICA-X",
      "size_meters": 3.6,
      "temp_degrees": 3000,
      "dev_partner": "NASA"
    },
    "thrusters": [
      {
        "type": "Draco",
        "amount": 18,
        "pods": 4,
        "fuel_1": "nitrogen tetroxide",
        "fuel_2": "monomethylhydrazine",
        "thrust": {
          "kN": 0.4,
          "lbf": 90
        }
      },
      {
        "type": "SuperDraco",
        "amount": 8,
        "pods": 4,
        "fuel_1": "dinitrogen tetroxide",
        "fuel_2": "monomethylhydrazine",
        "thrust": {
          "kN": 71,
          "lbf": 16000
        }
      }
    ],
    "launch_payload_mass": {
      "kg": 6000,
      "lb": 13228
    },
    "launch_payload_vol": {
      "cubic_meters": 25,
      "cubic_feet": 883
    },
    "return_payload_mass": {
      "kg": 3000,
      "lb": 6614
    },
    "return_payload_vol": {
      "cubic_meters": 11,
      "cubic_feet": 388
    },
    "pressurized_capsule": {
      "payload_volume": {
        "cubic_meters": 11,
        "cubic_feet": 388
      }
    },
    "trunk": {
      "trunk_volume": {
        "cubic_meters": 14,
        "cubic_feet": 494
      },
      "cargo": {
        "solar_array": 2,
        "unpressurized_cargo": true
      }
    },
    "height_w_trunk": {
      "meters": 7.2,
      "feet": 23.6
    },
    "diameter": {
      "meters": 3.7,
      "feet": 12
    },
    "wikipedia": "https://en.wikipedia.org/wiki/Dragon_2",
    "description": "Dragon 2 (also Crew Dragon, Dragon V2, or formerly DragonRider) is the second version of the SpaceX Dragon spacecraft, which will be a human-rated vehicle. It includes a set of four side-mounted thruster pods with two SuperDraco engines each, which can serve as a launch escape system or launch abort system (LAS). In addition, it has much larger windows, new flight computers and avionics, and redesigned solar arrays, and a modified outer mold line from the initial cargo Dragon that has been flying for several years."
  }
]

其中使用的技术栈：

后台框架使用的是 Koa。
内容缓存使用的是 Redis、Nginx 和 Cloudflare 。
测试使用的是 Jest 和 Supertest 。
使用 Circle CI 进行持续集成/部署。
数据库使用的是 **MongoDB **。

本地部署

首先clone项目

git clone https://github.com/r-spacex/SpaceX-API.git && cd SpaceX-API

安装并启动MongoDB数据库
安装依赖
```
npm i
```
or
```
yarn
```
运行测试
```
npm test
```
启动
```
npm start
```
or
```
yarn start
```

使用Docker部署

当然也可以使用Docker来进行部署：

git clone https://github.com/r-spacex/SpaceX-API.git && cd SpaceX-API
docker-compose build
docker-compose up

总结

虽然这个项目不是真的造火箭，但好歹也能吹吹牛逼。而且代码质量和工程结构都可以学习学习。

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