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JavaScript

Posted by john larson
john larson
16,594 Points

in this instance, what is "this" referring to?

//listItem is declared inside this function.  To this point in my learning
//it usually seems to be that "this" would be the object that is clicked on
//that's not happening here
// the object up the chain is the function itself
//so the parent node of the function?
//I'm so confused
//Do objects have parents?


var taskIncomplete = function() {
 //what is "this" referring to?
  var listItem = this.parentNode;
  incompleteTasksHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskCompleted);
}
john larson
john larson
16,594 Points

Tack så mycket , är du alltid insikts

1 Answer

Martin Cornejo Saavedra
Martin Cornejo Saavedra
18,132 Points
Martin Cornejo Saavedra
Martin Cornejo Saavedra
18,132 Points

It depends on the context. That function may be bind to a click event, then 'this' would be the clicked element.

For example, a checkbox:

var checkbox = document.getElementById("my_checkbox");
checkbox.onchange = taskIncomplete;
john larson
john larson
16,594 Points

Yes, that's what's happening here. Now that makes perfect sense. Thank you.

Jennifer Nordell
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.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher
Jennifer Nordell
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher

Hi John! Glad you got your question answered. Thought I'd throw in my two cents also. Had that not been attached to an event then the this would have referred to the global object (the window/document) which would have a parent node of undefined. Take a look at this small snippet in the console:

function func1(){
  return this;
}

console.log(func1());

Just a bit of trivia for you :sparkles:

Martin Cornejo Saavedra
Martin Cornejo Saavedra
18,132 Points
Martin Cornejo Saavedra
Martin Cornejo Saavedra
18,132 Points

Jennifer, that's interesting thanks for sharing.