Salesforce JavaScript Developer Practice Exam

What is the difference between var, let, and const in terms of scope?

1. All are function-scoped

2. All are globally scoped

3. var is function-scoped; let and const are block-scoped

4. var is block-scoped; let and const are globally scoped

The correct answer is: var is function-scoped; let and const are block-scoped

The distinction between `var`, `let`, and `const` primarily revolves around their scope, and option three accurately captures this nuance. `Var` is indeed function-scoped, meaning that if it is declared inside a function, it is accessible throughout that function. However, if it is declared outside any function, it becomes globally scoped and can be accessed throughout the entire script. In contrast, both `let` and `const` are block-scoped. This means that they are only accessible within the nearest enclosing block (enclosed by curly braces `{}`), such as within loops, conditionals, or any other block structure. This block scoping provides tighter control over variable visibility, helping to avoid unintentional changes or conflicts that can occur when variables are accessible more widely than intended. Therefore, option three correctly identifies that `var` is function-scoped while `let` and `const` are restricted to the block in which they are defined. This understanding is essential for effectively managing variable scope in JavaScript, particularly in more complex applications where function nesting and block structures are common.