How to calculate difference between saved timestamp and current time-CodePudding

Hey everyone i saved a timestamp in this format .

So what i wanna do now is calculating the difference between the current time and the saved timestamap in a javascript function. But i have no idea how to do.

Hope anyone can help.

CodePudding user response：

When you fetch the document, 'timestamp' field would be of type Timestamp and you can use seconds property and current timestamp to calculate the difference as shown below:

const snap = await getDoc(docRef);
const timeDiff = Date.now() - snap.data()?.time.seconds * 1000;

console.log(`Time Difference: ${timeDiff} ms`)

CodePudding user response：

This is actually very easy to achieve. Most important to know is that the function Date.now() returns you the number of milliseconds elapsed since January 1, 1970 00:00:00 UTC.

To get the duration between to timestamps is like "end - begin = duration".

Here is a code example:

// collect the first timestamp
const beginTimestamp = Date.now()

// here comes a for loop to consume some time, otherwise you will get 0 milliseconds
for (var i=0; i<10000; i  ) {
    "Some kind of string".split("").reverse().join("")
}

// collect the second timestamp
const endTimestamp = Date.now()

// subtract the first from the second timestamp tells you the milliseconds in between of both timestamps
console.log("Duration in milliseconds:", endTimestamp - beginTimestamp)