Parsing time-strings in Javascript

Question

So, I have this web server that parses an XML-file with a certain 'time-period'.

The time-period is presented as follows (I can't change this):

00:05:00 00:09:15 01:13:15 in an HH:MM:SS format.

I want to do an _.filter() select on all objects with a date between for instance 00:00:00 and 00:10:00, and then a filter with all objects between 00:10:00 and 00:20:00.

EDIT (clarification): With the time periods are 'times watched'. Let's say there are 50 entries of the time period, ranging from 00:00:00 to 1:30:00, but I want to make a new list that contains

The time period
The average 'times watched' in that time period.

This means I need some way to say: 'Select all time periods between zero minutes and 10 minutes. Give me a list of those. Compute the mean'.

For that, I would need to have some possibility to do arithmetic operations, seeing I would like to

Compare dates
Add 10 minutes on each iteration

However, the Javascript Date object doesn't seem to handle 'just times' that well, neither does the moment.js library. How would I go for this?

Could you clarify what you mean in your 4th paragraph (filter)? I'm taking that you want to run `_.filter()` twice, once checking for `00:00:00` to `00:10:00`, and the second `00:10:00` to `00:20:00`. Also, about "Add 10 minutes on each iteration", is that for all of them in the filter, or selected ones within the filter? — Qantas 94 Heavy, Aug 25 '13 at 13:54
possible duplicate of [Convert HH:MM:SS string to seconds only in javascript](http://stackoverflow.com/questions/9640266/convert-hhmmss-string-to-seconds-only-in-javascript) — WiredPrairie, Aug 25 '13 at 14:40

score 1 · Answer 1 · answered Aug 27 '13 at 04:33

Here is how I would do in JS:

times=['00:05:00', '00:09:15', '01:13:15'];

First get seconds

function getsec(time){
  arr=time.split(':');
  return (+arr[0])*3600 + (+arr[1])*60 + (+arr[2]);
}

times.map(getsec)
[ 300, 555, 4395 ]

Then filter times into slots of particular time period

function filter(last, curr, index, array){
  chk=parseInt(curr/600); //slots for 10 minutes
  if (typeof last[chk] === 'undefined')
  {
    last[chk]=[];
    last[chk].push(curr);
  }
  else
    last[chk].push(curr);
  return(last)
}

times.map(getsec).reduce(filter,[]);
[ [ 300, 555 ], , , , , , , [ 4395 ] ]

Returns array of arrays. Each child array contains times within slots in increasing order

Calculate mean

function avg(last, curr, index, array){
  if(index==array.length-1)
  return (last+curr)/array.length;
  else
  return last+curr;
}

times.map(getsec).reduce(avg,0);
1750

function getavg(arr){
  return arr.reduce(avg,0);
}

times.map(getsec).reduce(filter,[]).map(getavg);
[ 427.5, , , , , , , 4395 ]

Since we are dealing with array of arrays we need a wrapper.

Finally I would say that if you have many entries, databases would be faster.

kumarharsh · Answer 2 · 2013-08-26T07:25:40.303

-1

Simplest way would be for you to convert everything into seconds, and then do your thing.

inSeconds = function(time) {
  var secs, arr = [];
  arr = time.split(':').map(function(item) { return parseInt(item) });
  secs = arr[0]*3600 + arr[1]*60 + arr[2];
  return secs;
}

edited Aug 26 '13 at 07:25

answered Aug 25 '13 at 14:20

kumarharsh

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Oh my bad, I hadn't converted the string to int. – kumarharsh Aug 26 '13 at 07:25

Parsing time-strings in Javascript

2 Answers2