General Javascript ES6 'strict' Question.

[Pryme8]

So I have not been able to find an answer to a behavior I have come across...  I know this is not really a forum for this question but I figured someone here might know whats good.

So I have come across a really odd (at least I think it is) behavior when deleting variables references inside a new Object.
"SyntaxError: Delete of an unqualified identifier in strict mode."

Maybe I'm just dense and am deleting the var unnecessarily but here is the setup:

So lets say we have an index page where we include/link a few JS files.  

File1.js ->

class TEXTURE0_EMISSIVE extends ASSET{
	constructor (parent) {
		super(parent)
    	}
    	compile(){
 	
...some script

var somevar = 10
delete somevar 

...some script
	
    } 
}

Assuming there is already an Asset Object defined.

and then on the main page
Index ->

document.ready....{
    someParentObject(){
    var texture = new TEXTURE0_EMISSIVE(this);
          texture.compile();
    }
}


Basically a set up like this makes the page fail to compile the js file that has the delete referenced in it.  Ive never had this problem until I shifted to es6 structure.

I might just be dumb though and it could be simple (im prolly just not supposed to delete the var).....  I did not get much sleep the past couple days and my minds not working like it normally does.


*UPDATE* 
I think I figured it out... Im pretty sure GoDaddy is injecting "use strict" at some point on the document scope?  I say this because I can not reproduce on my local sever.

 

[Nabroski]

 we are in es8 already. var is now function scoped. i guess that's the mistake. But generally yes, you are the programmer, the strickt mode is meant for you to recognize usually java script errors, is nan is undef. javascript gives a damn. so put it in a strick mode. 

http://exploringjs.com/es6/ch_variables.html  

[Pryme8]

wtf we are in es8 are you for real?  I must of had my head under a rock.
https://www.ecma-international.org/ecma-262/8.0/index.html

Jeeeez... lots of reading to do.

[JCPalmer]

I recently went thru all my source for my QI extension. 

• Changed every reference of var to let or const unless it was  absolutely needed, 1 place.
• Changed to "for of" in every place where "for(let i = 0.." was just indexing.  tons of places (Typescript has an option for transpiling ' --downlevelIteration ' for ES3 & ES5).
• Changed to backquote for all strings concatenated with a "+".

Kind of a mechanical process, but helped by using an ide with good search.  Cleaning made the code more readable.  Does not replace reading, but for libraries it seemed worth it.

[Pryme8]

Sounds like I am going through the transition you just described! Thanks for the input.

[samme]

You can't delete a variable, only object properties.

[Nabroski]

remember rainy days back in 2 0 1 6 doing stuff like
const a = Array.from(somestuff).map( entries => ( { print: entries } ) );
console.log( a.print )
and now every day seems like sunshine:
Object.entries( ...[somestuff] ) or even [].concat(...somestuff.entries() );
they done pretty neat stuff with es8 or i just spend to much time on the babel side of the internet.

[Pryme8]

32 minutes ago, samme said:

You can't delete a variable, only object properties.

I am so dumb....  My god I knew this and have no clue what I was thinking...

I think its time to go take a nap.