Skip to content

Latest commit

 

History

History
23 lines (19 loc) · 626 Bytes

01-mutability.md

File metadata and controls

23 lines (19 loc) · 626 Bytes
title version
Mutability
1.0.0

The moment object in Moment.js is mutable. This means that operations like add, subtract, or set change the original moment object. When first using Moment.js many developers are confused by scenarios like this:

var a = moment('2016-01-01'); 
var b = a.add(1, 'week'); 
a.format();
"2016-01-08T00:00:00-06:00"

As you can see, adding one week mutated a. To avoid situations like that, clone the moment before performing date math:

var a = moment('2016-01-01'); 
var b = a.clone().add(1, 'week'); 
a.format();
"2016-01-01T00:00:00-06:00"