some-more-this-examples.txt

var a = {
    m: function() {
        console.log(this); // {m:f}
        (function(){
            console.log(this); // window object
        })();
    }
}
a.m();
// {m:f}
// window

var b = a.m;
b();
// window
//window

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function abc(param1,param2){
    console.log(this);
}
abc() // window
abc.call() // window
abc.call(null) // window
abc.call(1) // Number {1}

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'use strict';
function abc(param1,param2){
    console.log(this);
}
abc() // undefined
abc.call() // undefined


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var a = function() {
	console.log(this)
}
a(); // window

var b = {
    m: a
}

b.m(); // {m:f}

*Note if I bind this 'a' function with some other scope 

var a = function() {
	console.log(this)
}.bind({abc:'123'})


a(); //confusion start here:it should be window, but not window it will be {abc:'123'} whatever is bind with function a definition time

var b = {
    m: a
}

b.m();  //confusion start here: it should be {m:f}, but not,  it will be {abc:'123'} whatever is bind with function a definition time


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"use strict";
function sayHello(last_name) {
  console.log("Hello " + this + " " + last_name);
}.bind("Asim");
sayHello("Hussain");

// Error - as bind will return to a variable which is not captured.

here is solution:- 

"use strict";
var sayHello = function(last_name) {
  console.log("Hello " + this + " " + last_name);
}.bind("Asim");
sayHello("Hussain");

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