根据当前的“日期”动态呈现以下工作日

Question

I am creating a data visualisation and am trying to get the days 2-7 to render dynamically depending on the current day.

The dynamic function to get the current day is working and is saved as the variable called 'day'. However, I don't know what logic to use to create the following weekdays in my google chart depending on what the 'day' variable is.

// Temporary array of placeholder dates for the last 9 days

 let tempArray = [{time: "2020-11-28T04:13:30.000Z", value: 30},
                    {time: "2020-11-27T04:13:40.000Z", value: 77},
                    {time: "2020-11-26T04:13:50.000Z", value: 96},
                    {time: "2020-11-25T04:14:00.000Z", value: 64},
                    {time: "2020-11-24T04:14:10.000Z", value: 58},
                    {time: "2020-11-23T04:14:20.000Z", value: 45},
                    {time: "2020-11-22T04:14:30.000Z", value: 24},
                    {time: "2020-11-21T04:14:40.000Z", value: 19},
                    {time: "2020-11-20T04:14:50.000Z", value: 44},
                    {time: "2020-11-19T04:15:00.000Z", value: 49}]

// Function to turn ISO date format into an integer from 0-6 to get the day

    function getDayWeek(timeData, i){
      let date = timeData[i].time
      switch (new Date(date).getDay()) {
        case 0:
          day = "Sun";
          break;
        case 1:
          day = "Mon";
          break;
        case 2:
          day = "Tue";
          break;
        case 3:
          day = "Wed";
          break;
        case 4:
          day = "Thu";
          break;
        case 5:
          day = "Fri";
          break;
        case 6:
          day = "Sat";
      }
    }

...

// Render Google Chart

function drawChart(dayData) {

...

// Fires function

      getDayWeek(tempArray, 0)
      
    
// Graph row render

// 'day' variable returns Sat
// Code is missing the logic/function for dynamically rendering the following days

      let color = '#2196F3'
      var data = google.visualization.arrayToDataTable([
        ["Day", "Battery", { role: "style" } ],
        [day, data1, '#B33D3C'],
        [day2, data2, color],
        [day3, data3, color],
        [day4, data4, color],
        [day5, data5, color],
        [day6, data6, color],
        [day7, data7, color],
      ]);
...
  
  }

So, how do I dynamically render following weekdays depending on what the current 'day' is?

Let me know if you need me to explain further.

Answer 1

As I told you in comment, using momentJS is really nice. This one or another date library but not the native JS Date

Some example to get started

const now = moment();
const now_as_date = now.toDate(); // give a valid JS Date

const dayName = now.format('dddd');

const aDate = moment('2020-11-28T04:13:30.000Z');
//clone to not modify the aDate, important !
const previousDay = aDate.clone().add(-1, 'day');
const fourDaysLater = aDate.clone().add(4, 'days');

Here is how you can use it

function drawChart(dayData) {
  //You have a date somewhere, you use it with getDayWeek but I don't see it in the provided code
  //let's put something
  var date = new Date('2020-11-19T04:15:00.000Z');


  const dataTable = ["Day", "Battery", { role: "style" } ];
  
  new Array(7).fill().forEach( (e, i) => {
    const day = moment(date).add(i, 'days').format('ddd');
    //Where does data1,data2, come from?
    const data = '??';
    const color = (i===0) ? '#2196F3' : '#B33D3C';
    dataTable.push([day, data, color])
  });
  var data = google.visualization.arrayToDataTable(dataTable);
}

Answer 2

You can add day worth of milli seconds to get next date.

 const followingDays = (dateStr) => { const msInDay = 24 * 60 * 60 * 1000; return new Array(7).fill(0).map((_, i) => new Date(new Date(dateStr).getTime() + i * msInDay).toDateString() ); }; console.log(followingDays((new Date().toString()))); console.log(followingDays('2020-11-24'));