Java Reference
In-Depth Information
Generalized Functions
Callbacks can be used to build more generalized functions. Instead of having lots of spe-
cific functions, one function can be written that accepts a callback. For example, we could
add a callback parameter to the random() function, so that a calculation is performed on
the random number that's returned:
function random(a,b,callback) {
if (b === undefined) b = a, a = 1; // if only one
argument is
supplied, assume the lower limit is 1
result = Math.floor((b-a+1) * Math.random()) + a
if(typeof callback === "function") {
result = callback(result);
return result;
Now we have a function where more flexibility can be added using a callback. For ex-
ample, we can have a random square number from one to 100:
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Or a random even number from two to ten:
random(1,5, function(n) { return 2 * n });
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