matherton/index.html

## index.html
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">

<!-- The page title that is displayed in the top of the browser -->
  <title></title>
<!-- Meta content describes your page and is indexed by search engines such as Google -->
  <meta name="description" content="JS High Order function">
  <meta name="author" content="Mark Atherton">
  <!-- meta viewport ensures content is full screen width on mobile devises  -->
  <meta name="viewport" content="width=device-width, initial-scale=1">

<!-- link to external Cascading Style Sheet
  <link rel="stylesheet" href="css/styles.css?v=1.0"> -->

<!--[if lt IE 9]>
  <script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->
</head>

<!-- Opening body tag this where all your page content goes -->
<body>

<h1>company data in the console</h1>

<!-- Link to external JavaScript file  -->
  <script src="main.js"></script>
</body>
</html>

## main.js
const companies= [
  {name: "Company One", category: "Finance", start: 1981, end: 2004},
  {name: "Company Two", category: "Retail", start: 1992, end: 2008},
  {name: "Company Three", category: "Auto", start: 1999, end: 2007},
  {name: "Company Four", category: "Retail", start: 1989, end: 2010},
  {name: "Company Five", category: "Technology", start: 2009, end: 2014},
  {name: "Company Six", category: "Finance", start: 1987, end: 2010},
  {name: "Company Seven", category: "Auto", start: 1986, end: 1996},
  {name: "Company Eight", category: "Technology", start: 2011, end: 2016},
  {name: "Company Nine", category: "Retail", start: 1981, end: 1989}
];

const ages = [33, 12, 20, 16, 5, 54, 21, 44, 61, 13, 15, 45, 25, 64, 32];

/*ES5 way to use filter
financeCompanies = companies.filter(function(company) {
	if(company.category === "Finance") {
		return true;
	}
});*/

const financeCompanies = companies.filter(company => company.category === "Finance");
//console.log(financeCompanies);

const eightiesCompanies = companies.filter(company => (company.start >= 1980 && company.end < 1990));
//console.log(eightiesCompanies)

const lasted10Years = companies.filter(company => (company.end - company.start >= 10))
//console.log(lasted10Years)

const company = companies.map(function(company) {
 return company.name
})
//map filter returning a template literal

const companyNames = companies.map(company => `${company.name} [${company.start} - ${company.end}]`)
//console.log(companyNames)

const agesSquared = ages.map(age => Math.sqrt(age))
//console.log(agesSquared)

//sort array via start date

/*const sortedCompanies = companies.sort(function(c1, c2) {
	if(c1.start > c2.start) {
		return 1;
	} else {
		return -1;
	}
});*/
const sortedCompanies = companies.sort((a, b) => (a.start > b.start ? 1 : -1))
//console.log(sortedCompanies)
const sortAges = ages.sort((a, b) => a - b);
//console.log(sortAges);

// reduce

const ageSum = ages.reduce( (total, age) => total + age, 0);
//console.log(ageSum)

const allYears = companies.reduce(function(total, company) {
	return total + (company.end - company.start);
}, 0)
console.log(allYears);
//The above can be written like:
//Get total years for all companies
const totalYears = companies.reduce((total, company) => total + (company.end - company.start), 0)
console.log(totalYears)
	<!doctype html>
	<html lang="en">
	<head>
	<meta charset="utf-8">

	<!-- The page title that is displayed in the top of the browser -->
	<title></title>
	<!-- Meta content describes your page and is indexed by search engines such as Google -->
	<meta name="description" content="JS High Order function">
	<meta name="author" content="Mark Atherton">
	<!-- meta viewport ensures content is full screen width on mobile devises -->
	<meta name="viewport" content="width=device-width, initial-scale=1">

	<!-- link to external Cascading Style Sheet
	<link rel="stylesheet" href="css/styles.css?v=1.0"> -->

	<!--[if lt IE 9]>
	<script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script>
	<![endif]-->
	</head>

	<!-- Opening body tag this where all your page content goes -->
	<body>

	<h1>company data in the console</h1>

	<!-- Link to external JavaScript file -->
	<script src="main.js"></script>
	</body>
	</html>
	const companies= [
	{name: "Company One", category: "Finance", start: 1981, end: 2004},
	{name: "Company Two", category: "Retail", start: 1992, end: 2008},
	{name: "Company Three", category: "Auto", start: 1999, end: 2007},
	{name: "Company Four", category: "Retail", start: 1989, end: 2010},
	{name: "Company Five", category: "Technology", start: 2009, end: 2014},
	{name: "Company Six", category: "Finance", start: 1987, end: 2010},
	{name: "Company Seven", category: "Auto", start: 1986, end: 1996},
	{name: "Company Eight", category: "Technology", start: 2011, end: 2016},
	{name: "Company Nine", category: "Retail", start: 1981, end: 1989}
	];

	const ages = [33, 12, 20, 16, 5, 54, 21, 44, 61, 13, 15, 45, 25, 64, 32];

	/*ES5 way to use filter
	financeCompanies = companies.filter(function(company) {
	if(company.category === "Finance") {
	return true;
	}
	});*/

	const financeCompanies = companies.filter(company => company.category === "Finance");
	//console.log(financeCompanies);

	const eightiesCompanies = companies.filter(company => (company.start >= 1980 && company.end < 1990));
	//console.log(eightiesCompanies)

	const lasted10Years = companies.filter(company => (company.end - company.start >= 10))
	//console.log(lasted10Years)

	const company = companies.map(function(company) {
	return company.name
	})
	//map filter returning a template literal

	const companyNames = companies.map(company => `${company.name} [${company.start} - ${company.end}]`)
	//console.log(companyNames)

	const agesSquared = ages.map(age => Math.sqrt(age))
	//console.log(agesSquared)

	//sort array via start date

	/*const sortedCompanies = companies.sort(function(c1, c2) {
	if(c1.start > c2.start) {
	return 1;
	} else {
	return -1;
	}
	});*/
	const sortedCompanies = companies.sort((a, b) => (a.start > b.start ? 1 : -1))
	//console.log(sortedCompanies)
	const sortAges = ages.sort((a, b) => a - b);
	//console.log(sortAges);

	// reduce

	const ageSum = ages.reduce( (total, age) => total + age, 0);
	//console.log(ageSum)

	const allYears = companies.reduce(function(total, company) {
	return total + (company.end - company.start);
	}, 0)
	console.log(allYears);
	//The above can be written like:
	//Get total years for all companies
	const totalYears = companies.reduce((total, company) => total + (company.end - company.start), 0)
	console.log(totalYears)