meteor.com, as data

# Session ​This is useful in initialization code, to avoid re-initializing a session variable every time a new version of your app is loaded.## ​ Session.getGet the value of a session variable. If inside a [reactivecomputation](#reactivity), invalidate the computation the next time thevalue of the variable is changed by `Session.set`. Thisreturns a clone of the session value, so if it's an object or an array,mutating the returned value has no effect on the value stored in theThe name of the session variable to return<p>We've always been at war with {{theEnemy}}.</p>// Page will say "We've always been at war with Eastasia"// Page will change to say "We've always been at war with Eurasia"`## ​ Session.equalsTest if a session variable is equal to a value. If inside areactive computation, invalidate the computation the nexttime the variable changes to or from the value.The name of the session variable to testString, Number, Boolean, null or undefinedconst result = Session.equals();If value is a scalar, then these two expressions do the same thing:but the second one is always better. It triggers fewer invalidations (template redraws), making your program more efficient.<div class="{{postClass}}">{{title}}</div>Template.postsView.helpers({return Session.equals('selectedPost', this._id)Session.set('selectedPost', this._id);Using Session.equals here means that when the user clicks on an item and changes the selection, only the newly selected and the newly unselected items are re-rendered.If Session.get had been used instead of Session.equals, then when the selection changed, all the items would be re-rendered.`Session.equals` only accepts scalar values (strings, numbers, booleans, `null`, `undefined`, `Date`, `Mongo.ObjectID`) — passing an object or array throws `"ReactiveDict.equals: value must be scalar"`. For object or array values, use `EJSON.equals`, which performs a deep comparison on the application side: