Solved

Having trouble understanding javascript bind

Posted on 2013-12-10
6
237 Views
Last Modified: 2013-12-11
I took a look at the following url and explanation but still don't get it


https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind

Can somebody explain it better to me
0
Comment
Question by:stargateatlantis
  • 3
  • 3
6 Comments
 
LVL 29

Expert Comment

by:Göran Andersson
ID: 39709366
When you call a function as a method of an object, the context of the method is the object, and you can access the object using the this keyword.

Example:

var obj = {
  info: 'asdf',
  fn: function(){
    alert(this.info);
  }
};

obj.fn(); // alerts "asdf"

Open in new window


The bind method allows you to create a function reference that will act as if you called it as a method in an object, without the function actually being part of the object.

Example:

var obj = {
  info: 'asdf'
};

function showInfo() {
  alert(this.info);
}

var f = showInfo.bind(obj);
f(); // alerts "asdf"

Open in new window

0
 

Author Comment

by:stargateatlantis
ID: 39710207
Can you bind a object that contains a function??
0
 
LVL 29

Expert Comment

by:Göran Andersson
ID: 39710430
Yes, you can use any object as context for the function.

You could even use something like "a string" or 42 as context, then the context would be a String object or a Number object, respectively.

If you would use null or undefined as context, the function would get the window object as context.
0
Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

 

Author Comment

by:stargateatlantis
ID: 39710434
is there a more complex example
0
 
LVL 29

Accepted Solution

by:
Göran Andersson earned 500 total points
ID: 39711480
Here is an example with an object constructor and binding a function to an instance of the object:

function Employee(firstName, lastName) {
  this.firstName = firstName;
  this.lastName = lastName;
}

Employee.prototype = {

  showName: function(){
    alert(this.firstName + ' ' + this.lastName);
  }

};

// create an emplyee and show the name
var john = new Employee('John', 'Doe');
john.showName();

//bind a function expression to the employee
var showNameReverse = (function(){
  alert(this.lastName + ', ' + this.firstName);
}).bind(john);

// use it
showNameReverse();

Open in new window

0
 

Author Closing Comment

by:stargateatlantis
ID: 39712750
Thanks for the help that is what I was looking for
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

I've been trying to accomplish this for a while and it just struck me yesterday how to accomplish this task. I have done searches all over the internet looking for ways to email pages from my applications and finally I have done it!!! Every single s…
In Part 1 (http://www.experts-exchange.com/Programming/Languages/Scripting/JavaScript/A_7849-Hex-Maze.html) we covered the hexagonal maze basics -- how the cells are represented in a JavaScript array and how the maze is displayed.  In this part, we'…
The viewer will learn the basics of jQuery, including how to invoke it on a web page. Reference your jQuery libraries: (CODE) Include your new external js/jQuery file: (CODE) Write your first lines of code to setup your site for jQuery.: (CODE)
The viewer will learn the basics of jQuery including how to code hide show and toggles. Reference your jQuery libraries: (CODE) Include your new external js/jQuery file: (CODE) Write your first lines of code to setup your site for jQuery…

863 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

24 Experts available now in Live!

Get 1:1 Help Now