Parse array of JSON object in JavaScript

Question

I have a JSON string:

{
    "country": "Mauritius",
    "provinces": [
        "mainland"
    ],
    "timeline": {
        "cases": {
            "3/19/20": 3,
            "3/20/20": 12,
            "3/21/20": 14,
            "3/22/20": 28,
            [...]
            "4/17/20": 324
        },
        "deaths": {
            "3/19/20": 0,
            "3/20/20": 0,
            "3/21/20": 1,
            "3/22/20": 2,
            [...]
            "4/17/20": 9
        },
        "recovered": {
            "3/19/20": 0,
            "3/20/20": 0,
            "3/21/20": 0,
            "3/22/20": 0,
            [...]
            "4/17/20": 108
        }
    }
}

What I want to achieve is to parse the value of cases, deaths and recovered into separate arrays in JavaScript.

For example, the number of cases, I want to find the difference in the number of cases from the previous date, with starting date as 3/19/20 within an initial cases of 3. I want to apply same logic for deaths and recovered. Hence, 3/20/20 should have a value of 9 (12 - 3)

Finally, I want to store each of this in arrays to use this data on a chart. Can someone please help me to parse this data in JavaScript or JQuery?

 $.getJSON('https://corona.lmao.ninja/v2/historical/mauritius?lastdays=30', function(data) { let result = data.map(function(e) { return { cases: e.timeline.cases, deaths: e.timeline.deaths, recovered: e.timeline.recovered }; }).reduce(function(acc, e) { Object.keys(e).forEach(function(t) { Object.keys(e[t]).forEach(function(d) { acc[t][d] = (acc[t][d] || 0) - e[t][d]; }); }); return acc; }, { deaths: {}, recovered: {}, cases: {} }); console.log(result) });

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Answer 1

The following uses Array#reduce to transform the absolute values returned from the server, into the differences between days.

 const entries = Object.entries, log = console.log, toJSON = JSON.stringify const Δ = (arr, prev = 0) => arr.reduce((acc, [date, curr]) => (acc[date] = curr - prev, prev = curr, acc), {}) const AUTHORITY = 'corona.lmao.ninja' async function fetchDeltas({ country, days = 30 }) { const url = `//${AUTHORITY}/v2/historical/${country}?lastdays=${days}` const { timeline: { cases, deaths, recovered } } = await (await fetch(url)).json() return { newCases: Δ(entries(cases)), newDeaths: Δ(entries(deaths)), newRecoveries: Δ(entries(recovered)) } } fetchDeltas({ country: 'mauritius' }).then(log)

Answer 2

 (async function() { const {cases, deaths} = (await (await fetch("https://corona.lmao.ninja/v2/historical/mauritius?lastdays=30")).json()).timeline; console.log("Cases", diffEvents(cases)); console.log("Deaths", diffEvents(deaths)); })(); const diffEvents = (value) => { const dates = Object.keys(value); return dates.map((date, index) => { const currentDate = date; const prevDate = dates[index-1]; return { date: currentDate, count: index>0? value[date] - value[dates[index-1]]: value[date] }; }); };

Answer 3

 $.getJSON('https://corona.lmao.ninja/v2/historical/mauritius?lastdays=30', function(data) { function fn(x, i) { return [this[i][0], this[i][1] - (i-1<0? 0: this[i-1][1])]; } console.log( Object.fromEntries( Object.entries(data.timeline).map( ({0: type, 1: values}) => [ type, Object.fromEntries( (x=Object.entries(values)).map( fn.bind(x) ) )] ) ) ); });

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