Add --json option

[JamieMason]

Add --json option to output stats in serialised JSON format.

[jamesstout]

What sort of schema where you thinking of?

{
    "stats": {
        "files": [{
                "name": "jimmy.png",
                "prev": "217kB",
                "now": "56.6kB",
                "saving": "160kB",
                "perc": "73.91%"
            },
            {
                "name": "jimmy2.png",
                "prev": "233kB",
                "now": "65.9kB",
                "saving": "167kB",
                "perc": "71.74%"
            }
        ],
        "total": {
            "prev": "2.01MB",
            "now": "1.1MB",
            "saving": "908kB",
            "perc": "45.21%"
        }
    }
}

or

{
    "stats": [{
            "name": "png8_bril.png",
            "was": "60.9kB",
            "now": "54.9kB",
            "saving": "5.92kB",
            "perc": "9.73%"
        },
        {
            "name": "png8_grote-ogen.png",
            "was": "68.2kB",
            "now": "62kB",
            "saving": "6.23kB",
            "perc": "9.14%"
        },
        {
            "name": "TOTAL",
            "was": "539kB",
            "now": "450kB",
            "saving": "89kB",
            "perc": "16.51%"
        }
    ]
}

I've never done any TypeScript before, so I thought I'd learn a bit, so started on this: https://github.com/jamesstout/ImageOptim-CLI/tree/json-output

[JamieMason]

Sorry for the wait @jamesstout, there is a shape in use at https://github.com/JamieMason/ImageOptim-CLI/blob/master/src/get-stats.ts#L5-L23 which I was just thinking of exposing a CLI option for writing to disk. There'd be some adjustments needed for adding in the quality loss info but I think that would be better picked up as part of https://github.com/JamieMason/ImageOptim-CLI/issues/162.

That said, open to any ideas on any changes that might improve things.

Cheers J

[JamieMason]

Closing as YAGNI.