Failing to increment date with moment.js

问题:

Well, I just can't increment a date with moment.js. I get a javascript date object in my code, wrap it into moment function, calculate the amount of hours I need to add to the initial date and after I use .add method nothing happens. Tried doing something like currentTime.add(2, 'hours'), that didn't work as well. What am I doing incorrectly?

const currentTime = moment(ioc.get<Main.IArchiveManager>("ArchiveManager").getCurrentDate());
const speed = this.getData().speed;
const distance = this.calcDistanceFromPrevPoint(initialPoint,prevPoint);
const timeToReachPoint = (distance / speed) * 60;
const estimatedTime = currentTime.add(timeToReachPoint, 'hours');
debugger;
return estimatedTime;

this is a screenshot from my devtool so you know what is going on:

回答1:

You have to use format() (or .toString() or .toISOString()) to display the value of a moment object.

Note that:

• moment objects are mutable, so calling add will change the original object, if you need you can use the clone() method
• Do not use Internal properties (prefixed with _)

Your code is fine, you are just logging moment object the wrong way:

const currentTime = moment();
console.log(currentTime.format())
const speed = 0.1//this.getData().speed;
const distance = 20.56;// this.calcDistanceFromPrevPoint(initialPoint,prevPoint);
const timeToReachPoint = (distance / speed) * 60;
const estimatedTime = currentTime.add(timeToReachPoint, 'hours');
console.log(estimatedTime.format())

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js"></script>

回答2:

Everything is working as expected. You are logging the value of currentTime after it got changed. Remember that .add() changes the value of the object, it does not return a copy, but the object itself (for better chaining). See my example, you'll see that the came console.log, called twice but at different timings displays the values you'd expect.

var time = moment(new Date());
console.log(time);
time.add(2,'h');
console.log(time)

<script src="https://momentjs.com/downloads/moment.min.js"></script>