What is the result of the expression +true; !'Lydia';?

The expression consists of two parts: +true and !'Lydia'.

Starting with +true, the unary plus operator converts the boolean value true into a number. In JavaScript, true is equivalent to the numeric value 1, so +true evaluates to 1.

Next, the expression !'Lydia' involves the logical NOT operator. In JavaScript, non-empty strings are considered "truthy," meaning they evaluate to true in a boolean context. By applying the NOT operator, we negate the truthiness of the string 'Lydia'. This means !'Lydia' evaluates to false.

Thus, the complete expression produces the final result of 1 from the first part and false from the second part. Therefore, the overall result of the expression is 1 and false, which aligns with one of the answer choices provided.