The Date object is used to set and to get certain time values that you can use in your JS scripts.
There are two important things you should know before using this object:
1. The initial reference date is 1.1.1970. For previous date-time it uses negative values.
2. When you create a Date object, it uses the client computer (the visitor) date and time.
To use this object, you need to create an instance of the Date object, with the new keyword.
var dt = new Date(); document.write(dt); //similar with: Mon Jul 09 2018 17:54:20 GMT+0300 (GTB Daylight Time)
Date object has been created, you can use its methods to work with its components related to year, month, day, hour, minutes, seconds and milliseconds.getTime()) of the current date and displays the Timestamp (the number of seconds from 1-01-1970).
//defines a Date object with current time
const dt = new Date();
//gets the milliseconds, then the seconds
let mils = dt.getTime();
let sec = Math.trunc(mils /1000);
//writes the Timestamp
document.write('<p>Number of seconds since 1-01-1970: '+ sec +'</p>');
getFullYear() ), the month (with getMonth() ) and the current day number (with getDate() ), then adds them to an HTML element in the page (the first month has the value 0, the last month 11).
<p id='dv1'>YeaR, montrh and day number.</p>
<script>
//array with the names of the months
const ar_month =['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];
//defines a Date object with current time
var dt = new Date();
//gets the year, number of the month, and the day in month
let year = dt.getFullYear();
let month = dt.getMonth();
let day = dt.getDate();
//adds in #dv1 current month from 'ar_month' and day number
document.getElementById('dv1').innerHTML ='Current date: '+ year +'-'+ ar_month[month] +'-'+ day;
</script>
<p id='p1'>Example Date objet in JavaScript</p>
<script>
//array with days of the week
const days =['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
var ad_m = 90*60*1000; //an hour and 30 minutes in milliseconds
const dt = new Date();
//gets the milliseconds from current date-time, and adds ad_m
let mils = dt.getTime();
dt.setTime(mils +ad_m);
//gets the day of the week, hour, minutes, seconds
let wday = dt.getDay();
let hour = dt.getHours();
let mins = dt.getMinutes();
let sec = dt.getSeconds();
//displays the hour in #p1
document.getElementById('p1').innerHTML ='The day and time in an hour and 30 minutes: <b>'+ days[wday] +', '+ hour +':'+ mins +':'+ sec +'</b>';
</script>
For other specific (fixed) dates and time, a Date object can be created in 3 ways:
new Date(year, month, day, hours, minutes, seconds, milliseconds)
new Date(milliseconds)
new Date('date string')
Now it is presented with examples each of these modes.new Date(year, month, ...) creates a Date object with fixed date and time. Can get 7 arguments (integer numbers), the last 5 are optionals.var dt = new Date(2018, 7, 21, 11, 35, 20); //Represents: August 21, 2018, 11:35:20 var dt = new Date(98, 0, 8, 9); //Represents: 8 January 1998, 9:00:00 var dt = new Date(2019, 11, 25); //Represents: December 25, 2019
//defines a Date object for: 23 March 2018, 14:35
const dt = new Date(2018, 2, 23, 14, 35);
//gets the number of milliseconds, then the seconds
let mils = dt.getTime();
let sec = Math.trunc(mils /1000); // 1521808500
//writes the Timestamp
document.write('<p>The number of seconds from 1-01-1970 till 23-March-2018, 14:35 is: '+ sec +'</p>');
new Date(milliseconds) creates a new date object as zero time plus milliseconds.
//Date object with seconds * 1000 (for milliseconds)
const dt = new Date(1521808500 *1000);
document.write('<p>'+ dt +'</p>');
// Fri Mar 23 2018 14:35:00 GMT+0200 (GTB Standard Time)
//Date object with seconds * 1000 (for milliseconds)
const dt = new Date(-152180850 *1000);
document.write('<p>'+ dt +'</p>');
// Sat Mar 06 1965 17:32:30 GMT+0200 (GTB Standard Time)
new Date('date string') creates a new date object from a date string.
new Date('Month DD, YYYY hh:mm:ss'); // Aug 05, 2018 09:25:30
new Date('Month DD YYYY'); // Aug 05 2018
new Date('DD Month YYYY'); // 05 Aug 2018
new Date('YYYY-MM-DD'); // 2018-08-05
new Date('YYYY-MM-DDThh:mm:ss'); // 2018-08-05T09:25:30
//object with current date-time
const dt1 = new Date();
//define a Date object for 23 August 2018, 14:35
const dt2 = new Date('2018-08-25T14:35:00');
//gets the difference of milliseconds between dt1 and dt2
let mils = dt1.getTime() - dt2.getTime();
//gets seconds
let sec = Math.trunc(mils /1000);
//scrie numarul Timestamp
document.write('<p>The number of seconds from 23 August 2018, 14:35 till now: '+ sec +'</p>');
<ul> <li>http://coursesweb.net/html/</li> <li>http://coursesweb.net/css/</li> </ul>
.some_class {
display: list-item;
}var obj = {
"courses": ["php", "javascript", "ajax"]
};
var jsonstr = JSON.stringify(obj);
alert(jsonstr); // {"courses":["php","javascript","ajax"]}$strhtml = '<body><div id="dv1">CoursesWeb.net</div></body>';
$dochtml = new DOMDocument();
$dochtml->loadHTML($strhtml);
$elm = $dochtml->getElementById("dv1");
echo $elm->nodeValue; // CoursesWeb.net