This question already has an answer here:
I want to test a location feature in a web site, to make this test I need to try different time-zones. I obtain the timezone with a javascript code, calling the following function:
var offset = new Date().getTimezoneOffset();
Now this function returns to me 180 because I am in Argentina, I need to test with different time-zones. Somebody knows how to do this? Many thanks!!
The accepted answer doesn't really mock the Date.getTimezoneOffset
method, instead it expects you to use a different method with the same name.
It won't work on Date objects themselves and as Carl Meyer points out, it won't work for libraries like MomentJS.
A better way is to override the getTimezoneOffset
method on the Date
prototype, so that all instances of Date
have the overridden method.
d = new Date(); // Mon Jul 13 2015 10:58:12 GMT+0200 (CEST) alert(d.getTimezoneOffset()); // -120, My local "real" timezone. // Save the original method. var getTimezoneOffset = Date.prototype.getTimezoneOffset; Date.prototype.getTimezoneOffset = function () { return 160; } // Now Date objects will have the mocked timezone offset alert(d.getTimezoneOffset()); // 160, The mocked timezone. // Now restore the method to its original version Date.prototype.getTimezoneOffset = getTimezoneOffset; alert(d.getTimezoneOffset()); // -120
You could use a function for this.
function getTimezoneOffset() { if (DEBUG) { return 600; // for Australian Eastern Standard Time } return new Date().getTimezoneOffset(); }
Where DEBUG
is a variable set earlier on to determine whether you're testing or not.
Then use that function throughout your code, instead of the method on the Date object.