In Javascript, I want to calculate the difference between today'date (but adjusted to GMT0) and a given date 1970/01/01 in miliseconds.
On powershell for instance this will be (([datetime]::UtcNow) - (get-date "1/1/1970")).TotalMilliseconds
I tried to use moment.js like :
A = moment.utc();
B = moment('19700101', 'YYYYMMDD')
console.log("A is ",A)
console.log("B is ",B)
console.log("A format is ", A.format())
console.log("B format is ", B.format())
console.log("Milisec diff : ", A.diff(B,'miliseconds'))
It returns
A is h {_isAMomentObject: true, _useUTC: true, _isUTC: true, _l: undefined, _i: undefined, …}_d: Fri Nov 05 2021 10:43:43 GMT+0100 (heure normale d’Europe centrale) {}_f: undefined_i: undefined_isAMomentObject: true_isUTC: true_isValid: true_l: undefined_offset: 0_pf: {empty: false, unusedTokens: Array(0), unusedInput: Array(0), overflow: -2, charsLeftOver: 0, …}_strict: undefined_useUTC: true_z: null[[Prototype]]: Object
B is h {_isAMomentObject: true, _i: '19700101', _f: 'YYYYMMDD', _l: undefined, _strict: undefined, …}_a: (7) [1970, 0, 1, 0, 0, 0, 0]_d: Thu Jan 01 1970 00:00:00 GMT+0100 (heure normale d’Europe centrale) {}_f: "YYYYMMDD"_i: "19700101"_isAMomentObject: true_isUTC: false_isValid: true_l: undefined_pf: {empty: false, unusedTokens: Array(0), unusedInput: Array(0), overflow: -1, charsLeftOver: 0, …}_strict: undefined[[Prototype]]: Object
A format is 2021-11-05T09:43:43+00:00
B format is 1970-01-01T00:00:00+01:00
Milisec diff : 1636109023628
So the diff is not the good one, it takes A with the local hours (10:43 for me) and not the UTC hours (9:43). It is probably because you have to consider A.format to see 9:43 but we cannot give A.format to diff function.
Thanks for your help !
A small change in the above code should give you the result you wish:
A = moment.utc();
B = moment.utc(0)
console.log("A is ",A)
console.log("B is ",B)
console.log("A format is ", A.format())
console.log("B format is ", B.format())
console.log("Milisec diff : ", A.diff(B,'miliseconds')).as-console-wrapper { max-height: 100% !important; top: 0; }<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js" integrity="sha512-qTXRIMyZIFb8iQcfjXWCO8+M5Tbc38Qi5WzdPOYZHIlZpzBHG3L3by84BBBOiRGiEb7KKtAOAs5qYdUiZiQNNQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>You could also use an ISO 8601 timestamp with a UTC timezone ('Z'), like so:
A = moment.utc();
B = moment('1970-01-01T00:00:00Z')
console.log("A is ",A)
console.log("B is ",B)
console.log("A format is ", A.format())
console.log("B format is ", B.format())
console.log("Milisec diff : ", A.diff(B,'miliseconds')).as-console-wrapper { max-height: 100% !important; top: 0; }<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js" integrity="sha512-qTXRIMyZIFb8iQcfjXWCO8+M5Tbc38Qi5WzdPOYZHIlZpzBHG3L3by84BBBOiRGiEb7KKtAOAs5qYdUiZiQNNQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>A simpler way using the native JS Date object is to simply use Date.now(), this will give you the number of milliseconds since 1970-01-01 00:00:00 UTC.
console.log("Milisec diff : ", Date.now())