Học JavaScript qua ví dụ part 27

Các đối tượng Date JavaScript cung cấp cho các đối tượng ngày cho các thao tác ngày và Cũng giống như các chuỗi và mảng các đối tượng, bạn có thể tạo nhiều trường hợp như bạn muốn. Như chúng ta sẽ thấy, đối tượng Ngày cung cấp một số phương pháp để nhận hoặc thiết lập các thông tin cụ thể về ngày tháng và thời gian. | 234 Chapter 9 JavaScript Core Objects The Date Object JavaScript provides the Date object for manipulating date and Like the String and Array objects you can create as many instances as you like. As we ll see the Date object provides a number of methods for getting or setting specific information about the date and time. The date is based on the UNIX date starting at January 1 1970 in Greenwich Mean Time3 GMT and doesn t support dates before that time. Figure gives you an idea of the difference between GMT and local time. Time is measured in milliseconds one millisecond is one thousandth of a second . Because client-side JavaScript programs run on a browser the Date object returns times and dates that are local to the browser not the server. Of course if the computer is not set to the correct time then the Date object won t produce the expected results. Figure shows a typical date and time control panel. Figure 24-hour world time zones map with current time. Courtesy of http . 2. For more information about the time and date see http worldclock . 3. Greenwich Mean Time GMT is now called Universal Coordinate Time UTC . The current time in Greenwich England is five hours New York s present time or eight hours San Francisco s present time. From the Library of The Date Object 235 Figure The computer s date and time settings. If no arguments are passed to the Date object constructor it returns the local date and time based on the accuracy of the clock on your client machine . There are five formats that can be passed as arguments when creating a Date object shown in Example . EXAMPLE new Date Month dd yyyy hh mm ss new Date Month dd yyyy new Date yy mm dd hh mm ss new Date yy mm dd new Date milliseconds Here are a few examples of instantiating a date mydate new Date mydate new Date March 15 2010 09 25 00 mydate new Date March 15 2010 mydate new Date 10 2 15 .