What is the scope of a variable in JavaScript?

// Global scope
        var globalVar = "I am global";

        function testFunction() {
            // Function scope
            var functionVar = "I am local to the function";

            if (true) {
                // Block scope (ES6+)
                let blockVar = "I am local to the block";
                console.log(blockVar); // Accessible here
            }

            console.log(functionVar); // Accessible here
            // console.log(blockVar); // Error: blockVar is not defined
        }

        console.log(globalVar); // Accessible here
        // console.log(functionVar); // Error: functionVar is not defined