Is there any difference between this and self keyword usage in knockout js

Question

i just wonder is there any difference between self and this keyword usage or both same

see this example which use this keyword

var ViewModel = function(first, last) {
  this.first = ko.observable(first);
  this.last = ko.observable(last);
  this.full = ko.computed(function() {
     return this.first() + " " + this.last();
  }, this);
};

see this example which use self keyword instead of this keyword

var ViewModel = function(first, last) {
  var self=this;
  self.first = ko.observable(first);
  self.last = ko.observable(last);
  self.full = ko.computed(function() {
     return self.first() + " " + self.last();
  }, self);
};

which approach is good and why accepted ? thanks

Answer 1

Reading the documentation it seems that ko.computed essentially returns a bound function using the second arg as the context.

So, no, it does not seem to make any practical difference in this case.

There is a subtle difference inside the bound function:

self.full = ko.computed(function() {
     return self.first() + " " + self.last();
  }, self);

The self inside the function (self.first()) is creating a closure to the outer scope (where self is declared). So, the second argument defining context is then not really needed:

self.full = ko.computed(function() {
     return self.first() + " " + self.last();
  });

However, this could be changed to this without changing behaviour:

self.full = ko.computed(function() {
     return this.first() + " " + this.last();
  }, self);