Detailed explanation of JavaScript's built-in Date object

Date Object

Use Date object to represent a time in JS

Creating a Date Object

new Date()

Creating a Date object If you use the constructor to create a Date object, it will encapsulate the time when the current code is executed.

var d = new Date();
console.log("Current time is:",d);

Create a specified time object

You need to pass a string representing the time as a parameter in the constructor

Date format month/day/year (hour:minute:second)

var d = new Date("12/21/2012 12:12:30");
console.log("The Mayans predicted the end of the world:",d);

You can also create it by passing parameters

The syntax is

new Date(y,M,d,h,m,s):帶參的構造，參數是年、月、日、時、分、秒

var d = new Date(2012,11,21,8,00,00);
console.log(d);

Notice:

The integer value of the month of the time created by parameter passing, from 0 (January) to 11 (December)

getDate()

Get the date of the current object

var d = new Date("12/21/2012 12:12:30");
var date = d.getDate()
console.log("What is the date of object d:", date);

getDay()

• Get the day of the week of the current date object
• Will return a value from 0 to 6
  • 0 means Sunday
  • 1 for Monday
  • 2 for Tuesday
  • 3 for Wednesday
  • .......

var d = new Date("12/21/2012 12:12:30");
var date = d.getDay()
console.log("What day of the week is object d: ", date);

getMonth()

• Get the month of the current time object
• It will return a value between 0 and 11 (usually with 1 added to indicate the month commonly used in China)
  • 0 means January
  • 1 means February
  • ........
  • 11 means December

var d = new Date("12/21/2012 12:12:30");
var date = d.getMonth()
console.log("The month of the current time object is:", date); //Returns a number from 0 to 11, 11 represents December 

getFullYear()

• Get the year of the current date object
• This method has been replaced

var d = new Date("12/21/2012 12:12:30");
var date = d.getFullYear()
console.log("Year of the current time object:", date);

getHours()

• Get the hour of the current date object
• Return value (0~23)

getMinutes()

• Get the minute of the current date object
• Return value (0~59)

getSeconds()

• Get the seconds of the current date object
• Return value (0~59)

getMilliseconds()

• Get the milliseconds of the current date object
• Returns a value (0~999)

getTime()

• Get the timestamp of the current date and time
• Timestamp, which is the number of milliseconds from 0:0:0:00 Greenwich Mean Time, January 1, 1970 to the current object date (1 second = 1000 milliseconds)
• The computer bottom layer uses timestamps to save time.
• It can be converted to the current object time by (time/1000/60/60/24/365)

var d = new Date("12/21/2012 11:10:30");
var date = d.getTime()
console.log("Year of the current time object:", date);

Date.now()

• Get the current timestamp
• Timestamps can be used to test the performance of code execution

var start = Date.now();
for (let i = 0; i < 100; i++)
{
    console.log(i);
}
var end = Date.now();
console.log("The statement was executed: "+(end - start)+" milliseconds");

toDateString()

• Convert date to string

toLocaleDateString()

• Convert a date to a string in the local date format

Summarize

This article ends here. I hope it can be helpful to you. I also hope you can pay more attention to more content on 123WORDPRESS.COM!