Why use _this vs. this in Javascript interaction?

'this' is a reserved word that means the object in which that line of code is. With JavaScript you sometimes need to convery which 'this' you mean. There are generally two ways to do that, either Bind or use a variable.

For example:

alert(this);

testfunction();

on testfunction{

alert(this);

}

The two alerts will show different values. Using Bind:

alert(this);

testfunction.bind(this);

on testfunction{

alert(this);

}

will show the same value. But, using bind everywhere to keep the level being the same may not always be what you want, and so the other way of using a variable would do:

var _this = this;

alert(_this);

on testfunction{

alert(_this);

}

would show the same value. As 'this' is a reserved word it can't be used as a variable, and a common variable to use is _this. I sometimes use 'self' too, like:

var self = this;

Then I can refer to self when I'm trying to do something on the main timeline.

Another approach that is useful is to stash your variables in the browser window level. You could say:

window.tl = this;

and then everywhere in your entire hierarchy you could get back to the main timeline by addressing window.tl.