Format json with Vim (with python)

I want to bring an unformatted json and format it with vim for easy viewing.

For example, the value obtained by hitting some API
For example, the value listed in some document
For example, a hand-crafted value to leave a sample in the document

etc. In the first example, you can display it neatly by using the browser extension, but in the second and third cases, it seems convenient if you can paste it into vim and format it.

In the environment where python2.6 or later is installed (with the python command in the PATH), you can format the json string in the buffer by hitting the following command.

:%!python -m json.tool

For example, if you hit the above command when such a string is in the buffer

{"count":1,"list":[{"url":"http://json.org/example.html","title":"\u3042\u3044\u3046\u3048\u304a"}]}

I feel like this.

{
    "count": 1, 
    "list": [
        {
            "title": "\u3042\u3044\u3046\u3048\u304a", 
            "url": "http://json.org/example.html"
        }
    ]
}

It feels good. However, I'm not very happy with the Japanese being escaped (I'm also worried about the half-width space at the end of the line). So, I made a slightly improved command. I'm new to vim, so I'd be happy if you could get me a tsukkomi.

command! JsonFormat :execute '%!python -m json.tool'
  \ | :execute '%!python -c "import re,sys;chr=__builtins__.__dict__.get(\"unichr\", chr);sys.stdout.write(re.sub(r\"\\u[0-9a-f]{4}\", lambda x: chr(int(\"0x\" + x.group(0)[2:], 16)), sys.stdin.read()))"'
  \ | :%s/ \+$//ge
  \ | :set ft=javascript
  \ | :1

If you write a brief explanation

Formatted with python json.tool
Decode unicode strings like "\ u307d"
Delete because there is a space at the end of each line
Highlight vim filetype as javascript
Move the cursor to the first line

When you execute the command

:JsonFormat

The display will be as follows.

{
    "count": 1,
    "list": [
        {
            "title": "AIUEO",
            "url": "http://json.org/example.html"
        }
    ]
}