Giải thích mã nguồn

Overall purpose

This function accepts two values, a and b, and returns the result of applying JavaScript’s + operator to them. It can perform numeric addition or string concatenation, depending on the argument types.

Section-by-section walkthrough

• function add(a, b) declares a function named add with two parameters: a and b.
• { ... } contains the function body.
• return sends the computed value back to the caller.
• a + b applies the + operator to the two arguments.
• The final ; terminates the return statement.

For example:

add(2, 3);       // 5
add("Hi, ", "A"); // "Hi, A"

Clever bits

The function relies on JavaScript’s overloaded + operator. When both operands are numbers, it adds them; if either operand becomes a string, JavaScript generally converts the other operand to a string and concatenates them.

add(2, "3"); // "23", not 5

Because the function immediately returns the expression, it is compact and has no internal state or side effects.

One thing that could break

Unexpected argument types can produce surprising results because JavaScript performs implicit type coercion. For example, add(2, "3") returns "23" rather than 5; input validation or explicit conversion would be needed if the function must only perform numeric addition.