Mastering JavaScript

Anonymous functions as a parameter to
another function
This is one of the most popular patterns and you will find such code in most
professional libraries:
// function statement
function eventHandler(event){
event();
}
eventHandler(function(){
//do a lot of event related things
console.log("Event fired");
});
Chapter 2
You are passing the anonymous function to another function. In the receiving
function, you are executing the function passed as a parameter. This can be very
convenient if you are creating single-use functions such as object methods or event
handlers. The anonymous function syntax is more concise than declaring a function
and then doing something with it as two separate steps.
Anonymous functions in conditional logic
You can use anonymous function expressions to conditionally change behavior. The
following example shows this pattern:
var shape;
if(shape_name === "SQUARE") {
shape = function() {
return "drawing square";
}
}
else {
shape = function() {
return "drawing square";
}
}
alert(shape());
Here, based on a condition, we are assigning a different implementation to the shape
variable. This pattern can be very useful if used with care. Overusing this can result
in unreadable and difficult-to-debug code.
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