Format Dates without Timezone using JavaScript

Introduction

Formatting/creating dates with Javascript without timezone can be a bit tricky due to the difference between formatting in respect to a timezone or not, in this article we will demonstrate how to format/create JavaScript dates with respect to the user local timezone.

Method 1: Using Intl.DateTimeFormat.formatToParts()

The Intl.DateTimeFormat.prototype.formatToParts() method allows locale-aware formatting of strings produced by Intl.DateTimeFormat formatters.

The formatToParts() method is useful for custom formatting of date strings. It returns an Array of objects containing the locale-specific tokens from which it possible to build custom strings while preserving the locale-specific parts.

Here’s an example how DateTimeFormat.formatToParts works:

1- Create a Date object.

const date = new Date(2022, 11, 13);

2- Declare the shape of the formatted date parts.

const options = {
  weekday: 'long',
  year: 'numeric',
  month: 'numeric',
  day: 'numeric',
  hour: 'numeric',
  minute: 'numeric',
  second: 'numeric',
};

Here we’re telling the Intl.DateTimeFormat that we need the weekday to be long formatted, and the year to be a numeric value, and so on…

3- Create new Intl.DateTimeFormat instance

const dateTimeFormat = new Intl.DateTimeFormat('en-US', options);

We will pass to Intl.DateTimeFormat two parameters, the first one is the locale and the second is the options object we declared in step 2.

4- Call formatToParts function

const parts = dateTimeFormat.formatToParts(date);

Putting it all together, results in the following:

const date = new Date(2022, 11, 13);
const options = {
  weekday: 'long',
  year: 'numeric',
  month: 'numeric',
  day: 'numeric',
  hour: 'numeric',
  minute: 'numeric',
  second: 'numeric',
};

const dateTimeFormat = new Intl.DateTimeFormat('en-US', options);
const parts = dateTimeFormat.formatToParts(date);

console.log(parts);

// Expected Output 
[
    {
        "type": "weekday",
        "value": "Tuesday"
    },
    {
        "type": "literal",
        "value": ", "
    },
    {
        "type": "month",
        "value": "12"
    },
    {
        "type": "literal",
        "value": "/"
    },
    {
        "type": "day",
        "value": "13"
    },
    {
        "type": "literal",
        "value": "/"
    },
    {
        "type": "year",
        "value": "2022"
    },
    {
        "type": "literal",
        "value": ", "
    },
    {
        "type": "hour",
        "value": "12"
    },
    {
        "type": "literal",
        "value": ":"
    },
    {
        "type": "minute",
        "value": "00"
    },
    {
        "type": "literal",
        "value": ":"
    },
    {
        "type": "second",
        "value": "00"
    },
    {
        "type": "literal",
        "value": " "
    },
    {
        "type": "dayPeriod",
        "value": "AM"
    }
]

Looks Great! Now let’s add a simple functionality to build a readable formatted date based on the above output

const date = new Date(2022, 11, 13);

const options = {
  weekday: 'long',
  year: 'numeric',
  month: 'numeric',
  day: 'numeric',
  hour: 'numeric',
  minute: 'numeric',
  second: 'numeric',
};

const dateTimeFormat = new Intl.DateTimeFormat('en-US', options);
const parts = dateTimeFormat.formatToParts(date);

let formattedDate = '';
parts.forEach((part) => {
    if (part.type === "weekday") 
        formattedDate+= `${part.value}, `;
     if (part.type === "day") 
        formattedDate+= `${part.value}/`;   
     if (part.type === "month") 
        formattedDate+= `${part.value}/`;  
     if (part.type === "year") 
        formattedDate+= `${part.value}, `;
     if (part.type === "hour") 
        formattedDate+= `${part.value}:`;
     if (part.type === "minute") 
        formattedDate+= `${part.value}:`; 
     if (part.type === "second") 
        formattedDate+= `${part.value}`; 
});

console.log(formattedDate) // Expected Output 
Tuesday, 12/13/2022, 12:00:00

Method 2: By Manipulating javascript ISO date

To apply this way, let’s:

1- Create/Get the ISO representation of the date string.

const dateStr = '2022-08-20T01:44:31.820Z'; // Note the time is 01:44, 
//my time zone is 3 hours ahead of Coordinated Universal time (UTC).

2- Remove the Z character from the end of the ISO string.

const dateStr = '2022-08-20T01:44:31.820Z';
const result = new Date(date.toISOString().slice(0, -1)); // Removing Z character
console.log(result); // ️ Sat Aug 20 2022 01:44:31 GMT+0300

This shows that after passing a date string to the Javascript Date object and by removing the Z character we will get the same local time

But when Trying to pass the date string to the Date object while keeping the Z character, it will results in the date formatted according to Coordinated Universal time (UTC).

const dateStr = '2022-08-20T01:44:31.820Z';
const date = new Date(dateStr);
console.log(date); // ️ Sat Aug 20 2022 04:44:31 GMT+0300

So as a summary, If the Z is present, the Date is set to UTC. If the Z is not present, it’s set to local time (this only applies if the time is provided).

The Z at the end of the ISO string means UTC, in other words, an offset from UTC of zero hours, minutes and seconds.

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