Pfthb

Just out of curiosity:

In the context of a web browser, it is possible to add a property to the window object, consequently making it global, such as:

function a()
 window.b="c";

//edit
a();
console.log(b);

I was wondering if it is possible to set variables in a similar way, but only to the current scope, such as:

function a()
 scope.b="c";
 console.log(b);

//but "b" is not available here.

Possible use case

 var objectOne=new(function()
 this.a="e";
 this.b="f";
 this.c="g";
 )();
 (function()
 var importlist=["a","b"];
 var scopehere=scope;
 for(var importitm of importlist)
 scopehere[importitm]=objectOne[importitm];
 
 console.log(a,b);
 )();

So in this case, it would be possible to "import" many vars serially, have them accessible within the object as vars instead of using "this", (like when you export them to window), but in this case they are private.

In particular, if you are using an html-loaded script and you'd like to make the script properties available in the scope. Examples: paper.js, three.js. Going property by property would be a bit cumbersome, but it could be done automatically if there was such a "scope" object.

I know that you can work around in many ways, and perhaps there are not such substantial benefits to doing this. This question is merely out of curiosity.

Changes to this post:
added a call to function ´a()´ as pointed out by kylestephens.

This is just how scope works —— you don't need to do anything special just define a variable. Variables defined with let are scoped to their enclosing block. Those with var are scoped to the function:

function a()
 let b = "c";
 console.log(b);

a()
// console.log(b) error -- b not in scope 

If you have an object with a bunch of data, it's better to leave that data in some sort of structure rather than a bunch of individual variables. So the idea of importing a bunch of names into a scope isn't supported in general cases. In specific cases you can use destructuring:

// with array
function scope(importedList)
 let [a, b, c] = importedList // a, b, & c are local
 console.log(a, b, c)


scope([1, 2, 3])

// with object
function objscope(importedObject)
 let a, b, c = importedObject // a, b, & c are local
 console.log(a,b,c)


const someObj = 
 a: "e",
 b: "f",
 c: "g"
 

objscope(someObj)
 

In theory you can. However, in your first example the a() function is never called and thus the property 'b' is never set on the window object.

It would need to look like this:

function a()
 window.b="c";

a();
console.log(b);

Whether you should is another question. It is generally considered bad practice to pollute the global scope in this way. I recommend you look into prototypal inheritance and scopes and how you can use this to your advantage.