How to sort array of objects by time string value?

Question

I have an array of objects like so :

var example = [{
  "description": "aaa",
  "time": "12:15pm"
}, {
  "description": "bbb",
  "time": "10:10am"
}, {
  "description": "ccc",
  "time": "4:00pm"
}, {
  "description": "ddd",
  "time": "6:15pm"
}, {
  "description": "eee",
  "time": "1:10am"
}, {
  "description": "fff",
  "time": "5:00pm"
} ];

I want to sort by the time value.

I have tried to apply this solution which was intended for an array of string values:

example.sort(function (a, b) {
  return new Date('1970/01/01 ' + a.time) - new Date('1970/01/01 ' + b.time);
});

console.log(example);

I've also been referring to the Mozilla Array.prototype.sort() documentation and tried the following which didn't seem to work:

example.sort(function(a, b) {
  if (new Date(a.time) > new Date(b.time)) {
    return 1;
  }
  if (new Date(a.time) < new Date(b.time)) {
    return -1;
  }
  // a must be equal to b
  return 0;
});

console.log(example);

Your issue is that is not a valid date format to be parsed.

epascarello
– epascarello

2016-06-08 12:46:58 +00:00
Commented Jun 8, 2016 at 12:46 — epascarello
– epascarello, Commented Jun 8, 2016 at 12:46
new Date("1:10am"); //Invalid Date

Aramil Rey
– Aramil Rey

2016-06-08 12:48:09 +00:00
Commented Jun 8, 2016 at 12:48 — Aramil Rey
– Aramil Rey, Commented Jun 8, 2016 at 12:48
I will try with space before am/pm suffix.

user1063287
– user1063287

2016-06-08 12:48:53 +00:00
Commented Jun 8, 2016 at 12:48 — user1063287
– user1063287, Commented Jun 8, 2016 at 12:48

Pranav C Balan · Accepted Answer · 2023-07-20 09:58:31Z

8

The date string that you are generating is not valid so it will always returns current date and time. So generate valid date string(eg : '1970/01/01 9:34:48 AM') then parse and return the difference. Here String#slice() method can be used to generate the valid date string.

var example = [{
  "description": "aaa",
  "time": "12:15pm"
}, {
  "description": "bbb",
  "time": "10:10am"
}, {
  "description": "ccc",
  "time": "4:00pm"
}, {
  "description": "ddd",
  "time": "6:15pm"
}, {
  "description": "eee",
  "time": "1:10am"
}, {
  "description": "fff",
  "time": "5:00pm"
}];

example.sort(function(a, b) {
  // get time from string 
  // then get am or pm from string and append
  // both can be done using the slice method
  return Date.parse('1970/01/01 ' + a.time.slice(0, -2) + ' ' + a.time.slice(-2)) - Date.parse('1970/01/01 ' + b.time.slice(0, -2) + ' ' + b.time.slice(-2))
});

console.log(example);

edited Jul 20, 2023 at 9:58

answered Jun 8, 2016 at 12:49

Pranav C Balan

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Comments

Jagdish Idhate · Accepted Answer · 2016-06-08 13:05:41Z

1

You need a space before am/pm to make valid date .

We can put it in sort method before comparing as below.

example.sort(function(a,b){
  return new Date('1970/01/01 ' + a.time.replace(/(am|pm)/,' $1'))
 - new Date('1970/01/01 ' + b.time.replace(/(am|pm)/,' $1'))
})

edited Jun 8, 2016 at 13:05

answered Jun 8, 2016 at 12:57

Jagdish Idhate

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Comments

Rajesh Dixit · Accepted Answer · 2016-06-08 13:13:07Z

You can try to calculate value in 24hr format and sort it accordingly.

Logic:

Check if pm exists in string
If yes and hour is not 12, add 12 to it
Else return the number

var example=[{description:"aaa",time:"12:15pm"},{description:"bbb",time:"10:10am"},{description:"ccc",time:"4:00pm"},{description:"ddd",time:"6:15pm"},{description:"eee",time:"1:10am"},{description:"fff",time:"5:00pm"}];

example.sort(function(a,b){
  var t1 = get24HrFormat(a.time);
  var t2 = get24HrFormat(b.time);
  return t1>t2 ? 1 : t1<t2 ? -1 : 0;
});

function get24HrFormat(str){
  var _t = str.split(/[^0-9]/g);
  _t[0] =+_t[0] + (str.indexOf("pm")>-1 && +_t[0]!==12 ? 12: 0);
  return _t.join("");
}
  
document.write("<pre>" + JSON.stringify(example,0,4)+ "</pre>")

romellem · Accepted Answer · 2016-06-08 13:14:13Z

If you convert your time to hours and minutes (hours should be in 24-hour format) you don't even need to use the Date constructor.

Something like this:

example.map(c => {
  var time = c.time.substring(0,c.time.length - 2);
  var am_pm = c.time.slice(-2);

  var hours = parseInt(time.split(':')[0]);
  var minutes = parseInt(time.split(':')[1]);

  if (hours === 12 && am_pm.toLowerCase() === 'am') {
    hours = 0;
  } else if (hours < 12 && am_pm.toLowerCase() === 'pm') {
    hours += 12;
  }

  // save hours and minutes
  c.hours = hours;
  c.minutes = minutes;

  return c;
}).sort((a,b) => {
  return (a.hours * 100 + a.minutes) - (b.hours * 100 + b.minutes); 
});

Note, this modifies the examples array by adding hours and minutes properties.

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