Mastering JavaScript

Chapter 2
Functions as data
In JavaScript, functions can be assigned to variables, and variables are data. You will
shortly see that this is a powerful concept. Let's see the following example:
var say = console.log;
say("I can also say things");
In the preceding example, we assigned the familiar console.log() function to the
say variable. Any function can be assigned to a variable as shown in the preceding
example. Adding parentheses to the variable will invoke it. Moreover, you can pass
functions in other functions as parameters. Study the following example carefully
and type it in JS Bin:
var validateDataForAge = function(data) {
person = data();
console.log(person);
if (person.age 99){
return true;
}else{
return false;
}
};
var errorHandlerForAge = function(error) {
console.log("Error while processing age");
};
function parseRequest(data,validateData,errorHandler) {
var error = validateData(data);
if (!error) {
console.log("no errors");
} else {
errorHandler();
}
}
var generateDataForScientist = function() {
return {
name: "Albert Einstein",
age : Math.floor(Math.random() * (100 - 1)) + 1,
};
};
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