scope-discussion.md

Scopes Discussion

1. What is the scope of variable GLOBAL_DATA in the example below:

<script>
    let GLOBAL_DATA = {value : 1};
</script>

Pretend in the console, that we type:

console.log(GLOBAL_DATA);

2. What is the scope of variable x in the examples below:

let x = 1; // global
{
    let x = 2; //local
}
console.log(x); //1

var x = 1; // global
{
    var x = 2; // global
}
console.log(x); //2

3. What is the scope of variable x in the examples below:

function outerFn() {
    let x = 1;

    function log() {
        console.log(x);
    };

    function run(fn) {
        let x = 100;
        fn();
    }

    run(log);
};
outerFn(); //1

4. What do we call this method of scoping:

let x0 = 0;

function fn1() {
    let x1 = 1;
    fn2();

    function fn2() {
        let x2 = 2;
        fn3();

        function fn3() {
            let x3 = 3;
            console.log(x0 + " " + x1 + " " + x2 + " " + x3);
        };
    };
};
fn1();//0 1 2 3

5. What is the difference between global scope and other scope types and when do we use the global scope?

6. What is the difference between let and var defining a variable?

7. What is the difference between strict mode and sloppy mode?

1- The scope is global it can be accessed everywhere.

2- the Variable declared with Let is only accessed inside the block that is declared in so it can't be accessed outside that block, the Variable declared with Var can be also accessed outside the block that was declared in, the variables starting with var are not predictable so better not to use them at all.

3- the X in the outerfn is local for the function itself but it's considered global for its nested functions, and The X of the Run function is local for the Run function alone and it can't be accessed outside of it.

4- It's called the scope chain

5- A- The global: which can be accessed everywhere in your script, B- The Function Scope: can only be accessed inside the function box and the blocks that are in it. C- The Block scope: can only be accessed inside the curly brackets of the block.

6- Let: you can't redeclare it twice, hoisting does not occur, is block scoped BUTTTT var: you can declare it more than twice, hoisting occurs, is function scoped.

7- Strict will give us an error if there is any mistype or if we miss adding brackets or semicolons. but sloppy the javascript will assume what you meant and this may lead to weird bugs in the final project

ROOM 5
ali ibrahim, noor ridha, nma shawkat, zoriana Shatkovska

Q1: its A global SCOPE

Q2: the first example is local or function scope but the second one because it is declared with "var" will be a global variable.

Q3: its function scope.

Q4: Lexical

Q5: the global scope is the outermost scope, its variables can be accessed by the inner scopes like block scope and functional scope.

Q6: the var declaration declares the variable globally regardless of the block scope but the let declaration allows to declaration of variables that are limited to the scope or the block statement.

Q7: in the strict mode for example if you intentionally or unintentionally make a mistake in a code it can't be run but for sloppy mode, it can be run