JS Array Sort

JS Tutorial

JS Version

JS Objects

JS Function

JS Classes

JS Async

JS HTML DOM

JS Browser BOM

JS Web API

JS AJAX

JS JSON

JS vs JQUERY

JS Graphics

JavaScript Array Method

Sorting an Array

The sort() method is used to sort an array alphabetically:

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort</h2>

<p>The sort() method sorts an array alphabetically:</p>

<p id=”demo1″></p>

<p id=”demo2″></p>

<script>

const fruits = [“Banana”, “Orange”, “Apple”, “Mango”];

document.getElementById(“demo1”).innerHTML = fruits;

fruits.sort();

document.getElementById(“demo2”).innerHTML = fruits;

</script>

</body>

</html>

Output

JavaScript Array Sort

The sort() method sorts an array alphabetically:

Banana,Orange,Apple,Mango

Apple,Banana,Mango,Orange

Reversing an Array

The reverse() method is used to reverse the elements in an array

Sorting an array in descending order:

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort Reverse</h2>

<p>The reverse() method reverses the elements in an array.</p>

<p>By combining sort() and reverse() you can sort an array in descending order:</p>

<p id=”demo1″></p>

<p id=”demo2″></p>

<script>

// Create and display an array:

const fruits = [“Banana”, “Orange”, “Apple”, “Mango”];

document.getElementById(“demo1”).innerHTML = fruits;

// First sort the array

fruits.sort();

// Then reverse it:

fruits.reverse();

document.getElementById(“demo2”).innerHTML = fruits;

</script>

</body>

</html>

Output

JavaScript Array Sort Reverse

The reverse() method reverses the elements in an array.

By combining sort() and reverse() you can sort an array in descending order:

Banana,Orange,Apple,Mango

Orange,Mango,Banana,Apple

Numeric Sort

By default, the sort() function is used to sort the values as strings.

This works well for strings (“Apple” comes before “Banana”).

However, if numbers are sorted as strings, “25” is bigger than “100”, because “2” is bigger than “1”.

The sort() method generates incorrect result when sorting numbers.

You can solve this by providing a compare function:

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort</h2>

<p>Sort the array in ascending order:</p>

<p id=”demo1″></p>

<p id=”demo2″></p>

<script>

const points = [40, 100, 1, 5, 25, 10];

document.getElementById(“demo1”).innerHTML = points; 

points.sort(function(a, b){return a – b});

document.getElementById(“demo2”).innerHTML = points;

</script>

</body>

</html>

Output

JavaScript Array Sort

Sort the array in ascending order:

40,100,1,5,25,10

40,100,1,5,25,10

The Compare Function

The compare function is used to specify an alternative sort order.

The compare function return a negative, zero, or positive value, depending on the arguments:

function(a, b){return a – b}

When the sort() function compares two values, it is used to send the values to the compare function, and sorts the values according to the returned (negative, zero, positive) value.

If the result is negative a is sorted before b.

If the result is positive b is sorted before a.

If the result is 0 no changes are done with the sort order of the two values.

Example

The compare function compares all the values in the array, two values at a time (a, b).

When comparing 40 and 100, the sort() method calls the compare function(40, 100).

The function is used to calculate 40 – 100 (a – b), and since the result is negative (-60),  the sort function will sort 40 as a value lower than 100.

Using this code snippet to experiment with numerically and alphabetically sorting:

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort</h2>

<p>Click the buttons to sort the array alphabetically or numerically.</p>

<button onclick=”myFunction1()”>Sort Alphabetically</button>

<button onclick=”myFunction2()”>Sort Numerically</button>

<p id=”demo”></p>

<script>

const points = [40, 100, 1, 5, 25, 10];

document.getElementById(“demo”).innerHTML = points; 

 

function myFunction1() {

  points.sort();

  document.getElementById(“demo”).innerHTML = points;

}

function myFunction2() {

  points.sort(function(a, b){return a – b});

  document.getElementById(“demo”).innerHTML = points;

}

</script>

</body>

</html>

Output

JavaScript Array Sort

Click the buttons to sort the array alphabetically or numerically.

Sorting an Array in Random Order

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort</h2>

<p>Click the button (again and again) to sort the array in random order.</p>

<button onclick=”myFunction()”>Try it</button>

<p id=”demo”></p>

<script>

const points = [40, 100, 1, 5, 25, 10];

document.getElementById(“demo”).innerHTML = points; 

function myFunction() {

  points.sort(function(a, b){return 0.5 – Math.random()});

  document.getElementById(“demo”).innerHTML = points;

}

</script>

</body>

</html>

Output

JavaScript Array Sort

Click the button (again and again) to sort the array in random order.

The Fisher Yates Method

The array.sort(), is not accurate, it favor’s some numbers over the others.

The popular correct method is called the Fisher-Yates shuffle, and was introduced in data science as early as 1938!

In JavaScript the method can be translated to this:

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort</h2>

<h3>The Fisher Yates Method</h3>

<p>Click the button (again and again) to sort the array in random order.</p>

<button onclick=”myFunction()”>Try it</button>

<p id=”demo”></p>

<script>

const points = [40, 100, 1, 5, 25, 10];

document.getElementById(“demo”).innerHTML = points; 

function myFunction() {

  for (let i = points.length -1; i > 0; i–) {

    let j = Math.floor(Math.random() * i)

    let k = points[i]

    points[i] = points[j]

    points[j] = k

  }

  document.getElementById(“demo”).innerHTML = points;

}

</script>

</body>

</html>

Output

JavaScript Array Sort

The Fisher Yates Method

Click the button (again and again) to sort the array in random order.

Find the Highest (or Lowest) Array Value

There are no built-in functions that can be used to find the max or min value in an array.

However, after the array has been sorted, you can use the index to obtain the highest and lowest values.

Sorting ascending:

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort</h2>

<p>The lowest number is <span id=”demo”></span>.</p>

<script>

const points = [40, 100, 1, 5, 25, 10];

points.sort(function(a, b){return a-b});

document.getElementById(“demo”).innerHTML = points[0];

</script>

</body>

</html>

Output

JavaScript Array Sort

The lowest number is .

Sorting descending:

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort</h2>

<p>The highest number is <span id=”demo”></span>.</p>

<script>

const points = [40, 100, 1, 5, 25, 10];

points.sort(function(a, b){return b-a});

document.getElementById(“demo”).innerHTML = points[0];

</script>

</body>

</html>

Output

JavaScript Array Sort

The highest number is .

Using Math.max() on an Array

Using Math.max.apply can be used to find the highest number in an array:

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort</h2>

<p>The highest number is <span id=”demo”></span>.</p>

<script>

const points = [40, 100, 1, 5, 25, 10];

document.getElementById(“demo”).innerHTML = myArrayMax(points);

function myArrayMax(arr) {

  return Math.max.apply(null, arr);

}

</script>

</body>

</html>

Output

JavaScript Array Sort

The highest number is .

Using Math.min() on an Array

Using  Math.min.applycan be used to find the lowest number in an array:

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort</h2>

<p>The lowest number is <span id=”demo”></span>.</p>

<script>

const points = [40, 100, 1, 5, 25, 10];

document.getElementById(“demo”).innerHTML = myArrayMin(points);

function myArrayMin(arr) {

  return Math.min.apply(null, arr);

}

</script>

</body>

</html>

Output

JavaScript Array Sort

The lowest number is .

My Min / Max JavaScript Methods

The fastest solution is to use a “home made” method.

This function is used to loops through an array by comparing each value with the highest value found:

Find Max

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort</h2>

<p>The highest number is <span id=”demo”></span>.</p>

<script>

const points = [40, 100, 1, 5, 25, 10];

document.getElementById(“demo”).innerHTML = myArrayMax(points);

function myArrayMax(arr) {

  let len = arr.length;

  let max = -Infinity;

  while (len–) {

    if (arr[len] > max) {

      max = arr[len];

    }

  }

  return max;

}

</script>

</body>

</html>

Output

JavaScript Array Sort

The highest number is .

This function loops through an array comparing each value with the lowest value found:

Find Min

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort</h2>

<p>The lowest number is <span id=”demo”></span>.</p>

<script>

const points = [40, 100, 1, 5, 25, 10];

document.getElementById(“demo”).innerHTML = myArrayMin(points);

function myArrayMin(arr) {

  let len = arr.length;

  let min = Infinity;

  while (len–) {

    if (arr[len] < min) {

      min = arr[len];

    }

  }

  return min;

}

</script>

</body>

</html>

Output

JavaScript Array Sort

The lowest number is .

Sorting Object Arrays

JavaScript arrays consists of objects:

Example

const cars = [

  {type:”Volvo”, year:2016},

  {type:”Saab”, year:2001},

  {type:”BMW”, year:2010}

];

If objects consist of different data types, the sort() method sorts the array.

The solution is to compare function for comparing the property values:

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Array Sort</h2>

<p>Sort car objects on age:</p>

<p id=”demo”></p>

<script>

const cars = [

  {type:”Volvo”, year:2016},

  {type:”Saab”, year:2001},

  {type:”BMW”, year:2010}

];

displayCars();

cars.sort(function(a, b){return a.year – b.year});

displayCars();

function displayCars() {

 document.getElementById(“demo”).innerHTML =

  cars[0].type + ” ” + cars[0].year + “<br>” +

  cars[1].type + ” ” + cars[1].year + “<br>” +

  cars[2].type + ” ” + cars[2].year;

}

</script>

</body>

</html>

Output

JavaScript Array Sort

Sort car objects on age:


Notice: ob_end_flush(): failed to send buffer of zlib output compression (1) in /home/u212091429/domains/mydevhelp.com/public_html/wp-includes/functions.php on line 5420

Notice: ob_end_flush(): failed to send buffer of zlib output compression (1) in /home/u212091429/domains/mydevhelp.com/public_html/wp-includes/functions.php on line 5420