在JavaScript中显示当前日期和时间

Question

I have this script to display the current date and time in my web page:

<script type = "text/javascript">

function startTime() {
var now = new Date();
var h=now.getHours();
var min=now.getMinutes();
var s=now.getSeconds();
var ampm=(now.getHours()>11)?"PM":"AM";
var d=now.getDay();
var y=now.getFullYear();
var mon=now.getMonth();
var da=now.getDate();
var endings=["st","nd","rd","th"];
var dayendings=[0,1,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,4,0,2,3,4,4,4,4,4,4,1];
var days=["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"];
var months=["January","February","March","April", "May", "June","July","August","September", "October", "Novemeber","Decemeber"];
if (h>12) {h-=12}
if (h==0) {h=12};
if (min<10) {min="0"+min}
if (s<10) {s="0"+s}
da+=endings[dayendings[da]];
if (da<10) {da="0"+da};
d=days[d];
mon=months[mon-1];
document.getElementById("time").innerHTML=d+", "+mon+" "+da+", "+y+" "+h+":"+min+":"+s+" "+ampm;
var tim = setTimeout("startTime()",1000);
}

</script>

But the result is like this:

Friday, April NaN, 2012 6:37:36 PM

How can I make April NaN, 2012 right? It must be the date today which is May 25,2012

Answer 1

At the very least you should change

da+=endings[dayendings[da]];

to

da+=endings[dayendings[da - 1]];

because right now it has an off-by-one bug ( da is 1 to 31, but the indexes on dayendings are 0 to 30).

This should immediately fix your problem if "today" is the 31st of the month.

Fixes are also needed for the values in dayendings , as 4 is not meaningful there.

On a side note, you really should ditch this code for something better . Wouldn't you prefer it like this?

function startTime() {
    document.getElementById("time").innerHTML =
        moment().format("dddd, MMMM Do, YYYY h:mm:ss A");
}

Answer 2

Your var dayendings=[0,1,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,4,0,2,3,4,4,4,4,4,4,1]; includes some 4 values. Yet, var endings=["st","nd","rd","th"]; has only a length of 4, so that it will return undefined when you access endings[4] .

Also, you may get an off-by-one-error because da is in the range 1 to 31 , which are not the indizes of your dayendings array.

Answer 3

It appears that your logic for the counter is not correct. Try the following code:

function makeArray() {
for (i = 0; i<makeArray.arguments.length; i++)
this[i + 1] = makeArray.arguments[i];
}
var now = new Date();
var h=now.getHours();
var min=now.getMinutes();
var s=now.getSeconds();
var ampm=(now.getHours()>11)?"PM":"AM";
var months = new makeArray('January','February','March','April','May',
'June','July','August','September','October','November','December');
var date = new Date(); 
var day = date.getDate();
var month = date.getMonth() + 1;
var yy = date.getYear();
var year = (yy < 1000) ? yy + 1900 : yy;
var endings=["st","nd","rd","th"];
var dayendings=[0,1,2,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,4,0,2,3,4,4,4,4,4,4,1];
var days=["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday"];

document.write(days[date.getDay()] + " " + months[month]+ " " + day + ", " + year + " " + h + ":" + min + ":" + s + " " + ampm);

Answer 4

I've a relatively simple DateTime object in this jsfiddle . May be useful? In your case, using this object, this command would show the date in the format you want (apart from the PM/AM time formatting)

XDate({date:new Date,lang:'EN'}).format('WD, MM dd, yyyy, hh:mm:se0');
//=> Friday, May 25 2012, 13:05:03 

Answer 5

first generate this function and save as .js file

function date_time(id) {
    date = new Date;
    year = date.getFullYear();
    month = date.getMonth();
    months = new Array('January', 'February', 'March', 'April', 'May', 'June', 'Jully', 'August', 'September', 'October', 'November', 'December');
    d = date.getDate();
    day = date.getDay();
    days = new Array('Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday');
    h = date.getHours();
    if (h < 10) {
        h = "0" + h;
    }
    m = date.getMinutes();
    if (m < 10) {
        m = "0" + m;
    }
    s = date.getSeconds();
    if (s < 10) {
        s = "0" + s;
    }
    result = '' + days[day] + ' ' + months[month] + ' ' + d + ' ' + year + ' ' + h + ':' + m + ':' + s;
    document.getElementById(id).innerHTML = result;
    setTimeout('date_time("' + id + '");', '1000');
    return true;
}

then use this code on your html page to display the current time and date

<script type="text/javascript"> window.onload = date_time('date_time'); </script>

dont forget the script tag on the head part of your page: ex