Make JavaScript Date function accept string or date object

Question

I have this simple JavaScript function below that converts a JavaScript Date into a more readable format.

Right now you have to pass in a valid Date object but I would like to modify it so that it will accept a Date object or a string with a date value and return a formatted date regardless of which version is passed into it.

function formatDate(date) {
  var hours = date.getHours();
  var minutes = date.getMinutes();
  var ampm = hours >= 12 ? 'pm' : 'am';
  hours = hours % 12;
  hours = hours ? hours : 12; // the hour '0' should be '12'
  minutes = minutes < 10 ? '0'+minutes : minutes;
  var strTime = hours + ':' + minutes + ' ' + ampm;
  return date.getMonth()+1 + "/" + date.getDate() + "/" + date.getFullYear() + " " + strTime;
}

Usage:

var d = new Date(date_string);
var e = formatDate(d);

Converts this 2015-09-16 03:18:12 into 9/16/2015 3:18 pm

I want to be able to pass in a Date object...

var dateObject = new Date(date_string);
var e = formatDate(dateObject);

or a Date string...

var dateString = `2015-09-16 03:18:12`;
var e = formatDate(dateString);

adrield · Accepted Answer · 2015-09-16 20:58:41Z

2

You can check the type of variable before deciding which way to go:

function formatDate(date) {
    if(typeof(date) == "string") {
        var date_string = date;
        date = new Date(date_string);
    }
    // Then just keep going!
}

answered Sep 16, 2015 at 20:58

adrield

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Comments

tcooc · Accepted Answer · 2015-09-16 20:58:34Z

1

The way to do this is to do type checking in the function via typeof.

function formatDate(date) {
  if(typeof date === "string") {
    // parse the date string into a Date object
  }
  // now date is already a Date object, or it has been parsed
  var hours = date.getHours();
  ...

Actually parsing the Date string is outside the scope of the question.

answered Sep 16, 2015 at 20:58

tcooc

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