Fill missing dates in json string with jquery/javascript

Question

Here's a sample of what I have:

[{
  "probeTemp": "35.40",
  "dateProbe": "2015-08-1"
}, {
  "probeTemp": "34.89",
  "dateProbe": "2015-08-3"
}, {
  "probeTemp": "34.42",
  "dateProbe": "2015-08-5"
}]

How can I fill the missing dates between the min and max dates in the json string so the missing fields end up like this?

    [{
      "probeTemp": "35.40",
      "dateProbe": "2015-08-1"
    }, {
      "probeTemp": null,
      "dateProbe": "2015-08-2"
    }, {
      "probeTemp": "34.89",
      "dateProbe": "2015-08-3"
    }, {
      "probeTemp": null,
      "dateProbe": "2015-08-4"
    }, {
      "probeTemp": "34.42",
      "dateProbe": "2015-08-5"
    }]

I found this thread, but I don't know how I could apply it to my data. Any help?

Edit 2: This is what I tried so far, but I'm getting Uncaught TypeError: Cannot read property 'length' of undefined at lines 7 and 23.

Answer 1

We starts from getting first and last dates. Let

const a = [{
  "probeTemp": "35.40",
  "dateProbe": "2015-08-1"
}, {
  "probeTemp": "34.89",
  "dateProbe": "2015-08-3"
}, {
  "probeTemp": "34.42",
  "dateProbe": "2015-08-5"
}]; 

Then

const firstDate = a[0].dateProble; // "2015-08-1"
const lastDate = a[a.length-1].dateProbe; // "2015-08-5"

Now we can build range of all dates.

const dates = [ ...Array(
        Date.parse(lastDate)/86400000 - Date.parse(firstDate)/86400000 + 1).keys()    
    ].map(k => new Date(
            86400000*k+Date.parse(firstDate)
        ).toISOString().slice(0, 10).replace(/-0(\d)$/, '-$1')); 
// [ "2015-08-1", "2015-08-2", "2015-08-3", "2015-08-4", "2015-08-5" ] 

We created range with proper length, then moved it in timeline by number of milliseconds from epoch to first of dates. Finally we created Dates again transform to strings, sliced to get more natural format of dates and use regexp to remove leading 0 from number of days.

In last step we can define res - variable that contain our results. We define it as empty array and in for loop pushing next elements. Most important is probeTemp. If date that we considering from our range is equal date from array then we can add probeTemp and then increment j index, if it is new date than probeTemp is equall null and j index is not changed.

let res = []; 
for(let i=0,j=0; i<dates.length; i++) { 
    res[i] = {
        dateProbe: dates[i], 
        probeTemp: dates[i] === a[j].dateProbe ? a[j++].probeTemp : null
    }; 
}; 
console.table(res);

This solution works for sorted array a.