There is a solution in StackOverflow:

/\* use a function for the exact format desired... \*/
function ISODateString(d){
 function pad(n){return n<10 ? '0'+n : n}
 return d.getUTCFullYear()+'-'
      + pad(d.getUTCMonth()+1)+'-'
      + pad(d.getUTCDate())+'T'
      + pad(d.getUTCHours())+':'
      + pad(d.getUTCMinutes())+':'
      + pad(d.getUTCSeconds())+'Z'}

var d = new Date();
print(ISODateString(d)); // prints something like 2009-09-28T19:03:12Z
```But there is already a function for this: toISOString, it came with ecmascript 5. [Unfortunately, not all browsers support this](http://kangax.github.com/es5-compat-table/ "See the best comparision for ecmascript 5 support"), to solve this problem, we can provide our own prototype function for Date if it doesn't exist:

if (!Date.prototype.toISOString) { Date.prototype.toISOString = function() { function pad(n) { return n < 10 ? ‘0’ + n : n } return this.getUTCFullYear() + ‘-’ + pad(this.getUTCMonth() + 1) + ‘-’ + pad(this.getUTCDate()) + ‘T’ + pad(this.getUTCHours()) + ‘:’ + pad(this.getUTCMinutes()) + ‘:’ + pad(this.getUTCSeconds()) + ‘Z’; }; }