| title | description |
|---|---|
ReactiveVar |
Documentation of ReactiveVar, a simple reactive variable package. |
To use ReactiveVar, add the reactive-var package to your project by running
in your terminal:
meteor add reactive-var{% apibox "ReactiveVar" %}
A ReactiveVar holds a single value that can be get and set, such that calling
set will invalidate any Computations that called get, according to the
usual contract for reactive data sources.
A ReactiveVar is similar to a Session variable, with a few differences:
-
ReactiveVars don't have global names, like the "foo" in
Session.get('foo'). Instead, they may be created and used locally, for example attached to a template instance, as in:this.foo.get(). -
ReactiveVars are not automatically migrated across hot code pushes, whereas Session state is.
-
ReactiveVars can hold any value, while Session variables are limited to JSON or EJSON.
An important property of ReactiveVars — which is sometimes a
reason for using one — is that setting the value to the same
value as before has no effect; it does not trigger any invalidations.
So if one autorun sets a ReactiveVar, and another autorun gets the
ReactiveVar, a re-run of the first autorun won't necessarily trigger
the second. By default, only primitive values are compared this way,
while calling set on an argument that is an object (not a
primitive) always counts as a change. You can configure this behavior
using the equalsFunc argument.
{% apibox "ReactiveVar#get" %}
{% apibox "ReactiveVar#set" %}