Eloquent JavaScript, 3rd Edition

5HIGHER-ORDER FUNCTIONS

A large program is a costly program, and not just because of the time it takes to build. Size almost always involves complexity, and complexity confuses programmers. Confused programmers, in turn, introduce mistakes (bugs) into programs. A large program then provides a lot of space for these bugs to hide, making them hard to find.

Let’s briefly go back to the final two example programs in the introduction. The first is self-contained and six lines long.

let total = 0, count = 1;while (count <= 10) {  total += count;  count += 1;}console.log(total);

The second relies on two external functions and is one line long.

console.log(sum(range(1, 10)));

Which one is more likely to contain a bug?

If we count the size of the definitions ...