Chapter 2: JavaScript: Unique Parts

[valeryi]

Global Declaration: Global Scope

"In JavaScript, variables can be declared without using any operators"

The above statement is correct saying only about the "non-strict" mode. In the strict mode "use strict" would cause a ReferenceError.

Declaration with let: Block Scope

function scope3(print) {
    if(print) {
        let insideIf = '12';
    }
    console.log(insideIf)
}

scope3(true);

In the snippet above there would be a ReferenceError because as the title says let (and const) are Block Scoped variables.

Truthy/Falsy Check

"Here are commonly used expressions that evaluate to true:"

• true
• Any number other than 0
• Non-empty strings
• Non-empty object

Objects in JavaScript even if it's empty will always give the truthy result. Hence the last statement in the list is not correct.
I suppose it would be better to say:object (any object)