Java Reference
In-Depth Information
if (typeof callback === "function") {
total += callback(values[i]);
} else {
total += values[i];
}
Let's have a go at using it:
> mean([2,5,7,11,4]); // this should just calculate the
mean
<< 5.8
Now let's use an anonymous function to double all the numbers before calculating the
mean:
> mean([2,5,7,11,4],function(x){ return 2*x; });
<< 11.6
This is the equivalent of calculating the mean of 2 * 2, 2 * 5, 2 * 7, 2 * 11, and 2 * 4.
Last of all, let's use the
square
function that we wrote earlier in this chapter as a callback
to square all the numbers before calculating the mean:
> mean([2,5,7,11,4],square);
<< 43
This is the equivalent of calculating the mean of 2^2, 5^2, 7^2, 11^2, and 4x^2.
I trust these examples show how using callbacks can make functions much more powerful
and flexible.
