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JavaScript : Display the current date

JavaScript Basic : Exercise-3 with Solution

Write a JavaScript program to get the current date.
Expected Output :
mm-dd-yyyy, mm/dd/yyyy or dd-mm-yyyy, dd/mm/yyyy

Sample Solution: -

HTML Code:


<!DOCTYPE html>
  <html>
  <head>
  <meta charset="utf-8">
  <title>Write a JavaScript program to get the current date.</title>
  </head>
  <body>
  </body>
  </html>
  
  

JavaScript Code:


var today = new Date();
var dd = today.getDate();

var mm = today.getMonth()+1; 
var yyyy = today.getFullYear();
if(dd<10) 
{
    dd='0'+dd;
} 

if(mm<10) 
{
    mm='0'+mm;
} 
today = mm+'-'+dd+'-'+yyyy;
console.log(today);
today = mm+'/'+dd+'/'+yyyy;
console.log(today);
today = dd+'-'+mm+'-'+yyyy;
console.log(today);
today = dd+'/'+mm+'/'+yyyy;
console.log(today);

Sample Output:

01-09-2018
01/09/2018
09-01-2018
09/01/2018

Explanation:

Declaring a JavaScript date : In JavaScript Date objects are based on a time value that is the number of milliseconds since 1 January, 1970 UTC. You can declare a date in the following ways :

new Date();
new Date(value);
new Date(dateString);
new Date(year, month[, day[, hour[, minutes[, seconds[, milliseconds]]]]]);

The getDate() method is used to get the day of the month for the specified date according to local time. The value returned by getDate() is an integer between 1 and 31.

The getMonth() method returns the month in the specified date according to local time, as a zero-based value (where zero indicates the first month of the year). The value returned by getMonth() is an integer between 0 and 11. 0 corresponds to January, 1 to February, and so on.

The getFullYear() method is used to get the year of the specified date according to local time. The value returned by the method is an absolute number. For dates between the years 1000 and 9999, getFullYear() returns a four-digit number, for example, 1985.

Flowchart:

Flowchart: JavaScript - Display the current date

ES6 Version:

let today = new Date();
let dd = today.getDate();

let mm = today.getMonth()+1; 
const yyyy = today.getFullYear();
if(dd<10) 
{
    dd=`0${dd}`;
} 

if(mm<10) 
{
    mm=`0${mm}`;
} 
today = `${mm}-${dd}-${yyyy}`;
console.log(today);
today = `${mm}/${dd}/${yyyy}`;
console.log(today);
today = `${dd}-${mm}-${yyyy}`;
console.log(today);
today = `${dd}/${mm}/${yyyy}`;
console.log(today);

Live Demo:

See the Pen JavaScript program to get the current date - basic-ex-3 by w3resource (@w3resource) on CodePen.


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Next: Write a JavaScript function to find the area of a triangle where lengths of the three of its sides are 5, 6, 7.

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JavaScript: Tips of the Day

JavaScript: Quick Float to Integer

If you want to convert a float to an integer, you can use Math.floor() , Math.ceil() or Math.round() . But there is also a faster way to truncate a float to an integer using |, the bitwise OR operator.

console.log(23.9 | 0);  // Result: 23
console.log(-23.9 | 0); // Result: -23

The behaviour of | varies depending on whether you're dealing with positive or negative numbers, so it's best only to use this shortcut if you're sure.
If n is positive, n | 0 effectively rounds down. If n is negative, it effectively rounds up. To put it more accurately, this operation removes whatever comes after the decimal point, truncating a float to an integer.
You can get the same rounding effect by using ~~, as above, and in fact any bitwise operator would force a float to an integer. The reasons these particular operations work is that - once forced to an integer - the value is left unchanged.

Remove Final Digits
The bitwise OR operator can also be used to remove any amount of digits from the end of an integer. This means we don't have to use code like this to convert between types:

let str = "1553"; 
Number(str.substring(0, str.length - 1));

Instead, the bitwise OR operator allows us to write:

console.log(1553 / 10   | 0)  // Result: 155
console.log(1553 / 100  | 0)  // Result: 15
console.log(1553 / 1000 | 0)  // Result: 1

Ref: https://bit.ly/3nXQk8a