What will the console output be when evaluating the expression '2 + 2' using eval?

When the expression '2 + 2' is evaluated using the eval function, the result is a direct computation of the string as if it were actual JavaScript code. The eval function takes the string '2 + 2', parses it, and executes it in the current scope. Since '2 + 2' is a valid mathematical operation, it computes the sum and returns the value 4.

This direct execution is a key characteristic of the eval function: it interprets the string content as JavaScript code. In this case, the calculation happens seamlessly, leading to the output of 4 as the final result, which is exactly what one would expect if you were to perform that operation directly in the JavaScript console.

Other potential outputs like "2 + 2", an error, or undefined do not apply here because they either do not represent the evaluation of the expression correctly or they are a result of other contexts not related to the successful computation of a simple arithmetic operation.