Unable to understand difference between variable declaration and definition. Can anyone help?

Const declared vars cannot be redeclared in the same scope.

Something else already declared a variable named graph. Try "let someOtherGraph"

@SortOfTested but why it is throwing an error when I am trying to access `graph` value?

@Prakash
graph is being indirected by something. Possibly a proxy or a getter

@SortOfTested Can you explain it further?

A special rule applies when you declare a variable with let.
You can't redeclare a variable declared by let, for example let x =1; let x = 2; doesn't work.

@PrivateGER See 2nd line. I am unable to access the value of `graph`

Try to JSON.stringify it.

@PrivateGER unable to reproduce the issue again. Will try again tomorrow.

My guess is you ran `let graph` earlier which declares but doesn't define it.

The assignment (definition) fails because you're trying to re-declare it which isn't allowed. Drop the `let` for re-assignment.

Since you're in your browser's dev tools, reloading the page clears variables and lets you assign using `let` again

@DustInCompetent kindly read the second line, I am unable to access its value. Why is that happening?

declaration:
let myVar;
var myVar;

definition:
const myVar = null;
let myVar = null;
var myVar = null;

You cannot re-declare any variable in the same scope (a definition implies an declaration).

Your interactive console is also one scope (basically like the inspector-stylesheets, each line emulates a js file and the browser magic preserves your scope).

You can easily avoid this by using a collection var (var global ={}) or simply adding shit to you window.

Alternatively, you can also make an anonymous self-calling function that will receive the already declared variable. You (should) then be able to overwrite it - but for that scope, not affecting the parent.

Basically {} gives you a new scope. You can also declare the same variable name if you use a case 123: {doThat()}, which you cannot if you leave the curly braces.

Last tip: Store elements via the inspector, so they are temp1, temp2 and so on...