JavaScript Functions

Question 1

Functions can:
1)
2)
3)

Answer 1

Functions can:

1) hold a series of statements that perform some sort of processing.
2) may return data
3) may receive input via parameters

function functionName(parameter1, parameter2){ 
   statement1;
   statement2;
   statement3;
   return (value);   
}

Question 2

In JavaScript, functions can be treated as values. (Show example)

Answer 2

var addNumbers = function(a, b) {
 return(a+b);
};

addNumbers(1,2);

Question 3

A function can be passed into another function as a parameter (Show example)

Answer 3

var addingFunction = function (a,b){
 console.log(a+b);
}

var multiplicationFunction = function (a,b){
 console.log(a*b);
}

var calculate = function(calculationFunction, a, b) {
 calculationFunction(a,b);
};

calculate(addingFunction, 4,12);

calculate(multiplicationFunction, 4,12);

Question 4

A function can be returned by another function (Show example)

Functions that operate on other functions, either by taking them as arguments or by returning them, are called _____-order functions.

Answer 4

var power = function(power) {
 return function(number){
  console.log(Math.pow(number, power));
 }
};

var square = power(2);
var cube = power(3);

square(5);
cube(5);

Question 5

Functions as values in Objects (Show example)

Answer 5

var animal = {
 name:"Rover",
 age:5,
 humanYears : function(){
  return (15 + (this.age*4));
 }
}

console. log(animal.age);
console. log(animal.humanYears());

Question 6

Object Constructors (Show example)

Answer 6

function Circle(r) { 
 this.radius = r; 
 this.area = function() { 
  return Math.PI*this.radius*this.radius;
 }
}

c = new Circle(10);
c2 = new Circle(5); 

console. log(“Circle 1 Radius: “+c.radius);
console. log(“Circle 2 Area: “+c2.area());

Question 7

Closures and private variables (Show example)

Answer 7

function Circle(r) { 
 var radius = r;

return {

area: function(){
return Math.PIradiusradius;
},

setRadius: function(r){
radius = r;
}

}

}

c = new Circle(10);

console. log(“Circle Radius: “+c.radius);
console. log(“Circle Area: “+c.area());
c. setRadius(5);
console. log(“Circle Area: “+c.area());