Practicing Closure

Now let’s practice with closure (Chapter 4, Pillar 1).

The range(..) function takes a number as its first argument, representing the first number in a desired range of numbers. The second argument is also a number representing the end of the desired range (inclusive). If the second argument is omitted, then another function should be returned that expects that argument.

function range(start,end) {
    // ..TODO..
}
range(3,3);    // [3]
range(3,8);    // [3,4,5,6,7,8]
range(3,0);    // []
var start3 = range(3);
var start4 = range(4);
start3(3);     // [3]
start3(8);     // [3,4,5,6,7,8]
start3(0);     // []
start4(6);     // [4,5,6]

Try to solve this yourself first.

Once you have code that works, compare your solution(s) to the code in “Suggested Solutions” at the end of this appendix.