Why assign `this` to `self` and run `self.method()`?

Question

I\'m reading the source from mongoose

Collection.prototype.onOpen = function () {
  var self = this;
  this.buffer = false;
  self.doQueue();
};

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Answer 1

Just to give more clarity to @richard said earlier,

Collection.prototype.onOpen = function () {
  var self = this;
  this.buffer = false;
  this.onclick = function(){
     //do some other operations here
     //if you refer `this` here then, `this` will refer to present function not the above. so to make sure it is referring to exact object people pass this to `me` or `self`   
     self.doQueue();
  } 
 };