How to calculate the yesterday’s date in JavaScript ?

To calculate yesterday’s date in JavaScript you need to have some basic ideas of a few methods of javascript.

• JavaScript getDate() Method
• JavaScript setDate() Method

Problem Statement: In order to calculate yesterday’s date in JavaScript, we need to familiarize ourselves with 2 functions.

• getDate() It is an inbuilt JavaScript function that returns the day of the month as a number (1-31).

Syntax:

 dateObj.getDate() 

• setDate() It is an inbuilt JavaScript function used to set the day of the month into a date object. 

Syntax:

 dateObj.setDate()

Approach:

JavaScript allows us to create a platform-independent date instance that represents a single moment in time using Date constructor. An empty Date constructor creates a new date object that represents the current date and time. The Date constructor can also be specified to create a date object that represents a particular date and time. We use the getDate() function to fetch the current date from the date object and subtract one day from it using the setDate() function which sets yesterday’s date onto the date object.

Example 1: Here we will get yesterday’s date, in this example, we will show the output compared to today’s date. Syntax:

var dateObj = new Date(); 
// Empty Date constructor representing current time
dateobj; 
// Current Time => Wed Jun 12 2019 20:52:24 GMT+0530 (India Standard Time)

The following programs illustrate the solution

Javascript

<script>
    // JavaScript program to illustrate
    // calculation of yesterday's date

    // create a date object using Date constructor
    var dateObj = new Date();

    // subtract one day from current time
    dateObj.setDate(dateObj.getDate() - 1);

    alert(dateObj);

</script>

Output:

Calculate the yesterday’s date

Example 2: Here we will get the yesterday date of the pre-defined date which is Fri May 10, 2019, 16:30:00 GMT+0530 (India Standard Time). 

Syntax:

var dateObj = new Date(2019, 04, 10, 16, 30, 00);
// Specified Date constructor representing particular time   
dateObj; 
// Specific Time => Fri May 10 2019 16:30:00 GMT+0530 (India Standard Time)

Javascript

<script>
    // create a specified date object using Date constructor
    var dateObj = new Date(2019, 04, 10, 16, 30, 00);

    // subtract one day from specified time
    dateObj.setDate(dateObj.getDate() - 1);
    alert(dateObj);
</script>

Output: