How can I do to evaluate the time?

Question

Hello I have this code using javascript :

var begin1 = new Date('December 17, 1995 08:00:00');    
var begin2 = new Date('December 17, 1995 08:01:00');
var begin3 = new Date('December 17, 1995 10:00:00');
var begin4 = new Date('December 17, 1995 16:00:00');

var end1 = new Date('December 17, 1995 08:30:00');
var end2 = new Date('December 17, 1995 09:00:00');
var end3 = new Date('December 17, 1995 11:00:00');
var end4 = new Date('December 17, 1995 16:30:00');

begin = [begin1, begin2, begin3, begin4];
end = [end1, end2, end3, end4];

Basically, I have many slots like begin1 - end1, begin2 - end2, begin3 - end3, begin4 - end4.

What I am trying to do is to evaluate the time like this :

for begin1 (08:00:00) - end1 (08:30:00) : 30 minutes

for begin2 (08:01:00) - end2 (09:00:00) : 59 minutes but if I look at the var begin1 there is the part (08:00:00) - (08:30:00) so for begin2 (08:01:00) - end2 (09:00:00) we count only the part (08:30:00) - (09:00) so it is 30 minutes

for begin3 (10:00:00) - end3 (11:00:00) : one hour

for begin4 (16:00:00) - end3 (16:30:00) : 30 minutes

so if I evaluate the sum I get 30 minutes + 30 minutes + 1 hour + 30 minutes = 2h30.

How can I do to get this result using javascript ?

Thank you a lot !

EDIT : Basically, I mean I have many dates for one day and I want to evaluate the time for this date for instance if I have 08:00:00-08:30:00 it is 30 minutes but if have also 08:10:00-09:00:00 I want to have just 08:30:00-09:00:00 because I have 08:00:00 -08:30:00 yet. So the duration will be one hour.

EDIT1 : This picture will explain exactly what I want :

result

Answer 1

Your post is not clear.

If I understood it well you can do like this:

var date1 = new Date('December 17, 1995 03:24:00');
var date2 = new Date('December 17, 1995 03:34:00');
minutes = ((date2-date1)/1000)/60; //Get minutes of difference 

EDIT

I create a sample script but is not tested well. It should work if you have the data ordered according to begin:

function f(){
  var begin1 = new Date('December 17, 1995 08:00:00');  
  var begin2 = new Date('December 17, 1995 08:01:00');
  var begin3 = new Date('December 17, 1995 08:10:00');
  var begin4 = new Date('December 17, 1995 10:00:00');
  var begin5 = new Date('December 17, 1995 16:00:00');

  var end1 = new Date('December 17, 1995 08:30:00');
  var end2 = new Date('December 17, 1995 09:00:00');
  var end3 = new Date('December 17, 1995 09:20:00');
  var end4 = new Date('December 17, 1995 11:00:00');
  var end5 = new Date('December 17, 1995 16:30:00');

  begin = [begin1, begin2, begin3, begin4, begin5 ];
  end = [end1, end2, end3, end4, end5];

  duration = [[begin1, end1]];
  console.log(duration.length);
  for(i=1 ; i<begin.length; i++){
    for(j=0; j<duration.length; j++){
      if(begin[i]>= duration[j][0] && begin[i]<= duration[j][1] ){
         if(end[i]<= duration[j][1] ){
           break;
         }else{
           duration[j][1] = end[i];
           break;
         }
    }else{
      if(j==duration.length-1){
        console.log(begin[i]);
        duration.push([begin[i], end[i]]);
        break;
      }else{
        continue;
      }

    }
  }
  }
  var diff = 0;
  var i = 1;
  duration.forEach(function(element){
      console.log("Time range " + i + ": " + element);
      diff= diff + (element[1]- element[0])/1000/60;
      i++;
  });
    console.log("Total Minutes: " + diff);
  }

f();

Answer 2

To start out, understand that parsing dates in that manner is potentially problematic. Some good reads on the subject are here:

• What are valid Date Time Strings in JavaScript?
• Why does Date.parse give incorrect results?

---

But, assuming you understand the limitations and that the objects returned from your code provide acceptable results for you the answer is fairly straightforward.

The first thing to know is that you can directly subtract one date from another to get the difference (in ms). Some simple arithemtic will convert this to seconds, or minutes.

var begin1 = new Date('December 17, 1995 08:00:00');    

var end1 = new Date('December 17, 1995 08:30:00');

var diffMs = end1 - begin1;
console.log(diffMs + "ms")

var diffS = diffMs/1000;
console.log(diffS + "s");

var diffM = diffS/60;
console.log(diffM + "mins");

Now, to do this across your arrays, you could use a function that zips them together and applies a function which calculates the difference

var begin1 = new Date('December 17, 1995 08:00:00');    
var begin2 = new Date('December 17, 1995 08:01:00');
var begin3 = new Date('December 17, 1995 10:00:00');
var begin4 = new Date('December 17, 1995 16:00:00');

var end1 = new Date('December 17, 1995 08:30:00');
var end2 = new Date('December 17, 1995 09:00:00');
var end3 = new Date('December 17, 1995 11:00:00');
var end4 = new Date('December 17, 1995 16:30:00');

var begin = [begin1, begin2, begin3, begin4];
var end = [end1, end2, end3, end4];

var zip = (array1,array2, func) => array1.map( (v,i) => func(v,array2[i]));

var diffs = zip(begin,end, (b,e) => e - b);
console.log(diffs);

var result = diffs.reduce( (acc,e) => acc + e,0);
console.log("Total MS", result);
console.log("Total S", result/1000);
console.log("Total M", result/1000/60);

Above you can see the result is a new array with 4 elements - each being the difference in milliseconds. You can then reduce this to get the sum in Ms (result).

You may then use the arithmetic specified at the beginning of this answer to display this how you wish.