Scope & Context

Relax. We'll talk through this in plain words — no textbook voice.

Scope determines where in your code a variable can be accessed.

🎯 Scope Types:

• Global Scope: Everywhere accessible

• Function Scope: Inside function only

• Block Scope: Inside {} (let/const)

• Lexical Scope: Nested functions access outer variables

javascript

// Global scope
let globalVar = "I'm global";

function demoScope() {
    // Function scope
    var functionVar = "I'm in function";
    
    if (true) {
        // Block scope
        let blockVar = "I'm in block";
        const alsoBlock = "Me too";
        var notBlock = "I'm function scoped";
        
        console.log(globalVar);    // OK
        console.log(functionVar);  // OK
        console.log(blockVar);     // OK
    }
    
    console.log(functionVar); // OK
    console.log(notBlock);    // OK
    // console.log(blockVar); // Error!
}

demoScope();
console.log(globalVar); // OK
// console.log(functionVar); // Error!

// Lexical scope
function outer() {
    let outerVar = "outer";
    
    function inner() {
        let innerVar = "inner";
        console.log(`${outerVar} + ${innerVar}`);
    }
    
    inner();
}
outer();

You should see

I'm global I'm in function I'm in block I'm in function I'm function scoped I'm global outer + inner