this.lastData, theInstance.lastData and self.lastData

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frcol
- Joined 10 Dec, 2014
- 30 topics • 143 posts
1

13 Jan, 2016
Quote

Studying the AJAX plugin as refence, i found "lastData" in 3 situations:

Code 1

pluginProto.Instance = function(type)
	{	
       ...
		this.lastData = "";[/code:3l7lvv5y]

Code 2
[code:3l7lvv5y]
var theInstance = null;

window["C2_AJAX_DCSide"] = function (event_, tag_, param_)
	{
         ...
			theInstance.lastData = param_;
	}

instanceProto.onCreate = function()
	{
		theInstance = this;
	};
[/code:3l7lvv5y]

Code 3
[code:3l7lvv5y]
var self = this;

var errorFunc = function ()
		{
    self.lastData = data.replace(/\r\n/g, "\n")[/code:3l7lvv5y]

Code 4
[code:3l7lvv5y]Exps.prototype.LastData = function (ret)
	{
		ret.set_string(this.lastData);
	};[/code:3l7lvv5y]

The first 2 codes I think it´s talking about the "Instances" propertie (between the 3 Classes: Plugin, type and Intance).

Why in code 3 is using "self" ?

In code 4 the "this.lastData" refers to the instace too?

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- R0J0hound
- - Joined 15 Jun, 2009
  - 90 topics • 7,271 posts
- 1
- 13 Jan, 2016
- Quote
In 1 and 4 "this" is the current instance.

In 2 "this" in the onCreate function is the current instance. It's set to a global variable so the instance can be referenced in that widow callback.

In 3 self is used so the callback "errorFunc" can access the instance. Otherwise I think this would be the global window object.

The following link probably is better help:

http://javascriptissexy.com/understand- ... master-it/
- frcol
- - Joined 10 Dec, 2014
  - 30 topics • 143 posts
- 1
- 14 Jan, 2016
- Quote
Thanks R0J0hound, just perfect!

The problem was the nested function.

When "this" is inside a nested expression function (example called "A"), that is inside the "instanceProto" function, Calling the "A" function will get you the global object, in Strict mode, undefined (that was the trick part). That´s the reason for defining the "self"...you are right.