Javascript Array Sort

The Basics of Javascript Array Sort Method

let arrayToSort = ['Banana', 'Apple', 'Date', 'Carrot', 'Eggplant'];
arrayToSort.sort();

Javascript array sort method explained

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

The Parameters of array.sort in Javascript

function compare(a, b){
  if (a is less than b by some ordering criterion) {
    return -1;
  }
  if (a is greater than b by the ordering criterion) {
    return 1;
  }
  // a must be equal to b
  return 0;
}

Working with Javascript Array Sort Function

How to Use the Javascript Array Sort Function

let someArray = ['item3', 'item2', 'item1'];
someArray.sort();

let someNumbers = [30, 2, 10000, 50];
someNumbers.sort(function(a, b) {
  return a - b;
});

Simple examples of using the Javascript array sort function

// 1. Alphabetical Sorting
let fruits = ['Banana', 'Apple', 'Pineapple', 'Zucchini'];
fruits.sort();
console.log(fruits);

// 2. Sorting Numbers (Ascending)
let numbers = [50, 2, 100, 10];
numbers.sort(function(a, b) {
  return a - b;
});
console.log(numbers);

The Return Value of the Javascript Array Sort Function

let numbers = [50, 2, 100, 10];
let sortedNumbers = numbers.sort(function(a, b) {
  return a - b;
});
console.log(sortedNumbers);

Javascript Array Sort Algorithm

Understanding the Javascript Array Sort Algorithm

• If it returns a negative value, 'a' is sorted to be before 'b'.
• If it returns a positive value, 'b' is sorted to be before 'a'.
• If it returns '0', the position of 'a' and 'b' relative to each other remains unchanged.

let arr = [30, 1, 100, 40];
arr.sort(function(a, b) {
  return a - b;
});

Benefit of the Javascript Array Sort Algorithm

Coding Javascript Array Sort

Mastering the Javascript Sort Object Array Method

let students = [
  {name: 'John', age: 23},
  {name: 'Amy',  age: 22},
  {name: 'Bill', age: 24}
];

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

[
  {name: 'Amy',  age: 22},
  {name: 'John', age: 23},
  {name: 'Bill', age: 24}
]

Examples of Javascript Array Sort Methods in Code

//Numbers (Ascending)
let nums = [10, 1, 5];
nums.sort(function(a, b) {
  return a - b;
});
console.log(nums); // [1, 5, 10]

//Strings (Alphabetical order)
let fruits = ['Banana', 'Apple', 'Pineapple'];
fruits.sort();
console.log(fruits); // ['Apple', 'Banana', 'Pineapple']

//Array Objects (sorting by 'age')
let students = [
  {firstName: 'John', age: 23},
  {firstName: 'Amy',  age: 22},
  {firstName: 'Bill', age: 24}
];
students.sort(function(a, b) {
  return a.age - b.age;
});
console.log(students);

[
  {firstName: 'Amy',  age: 22},
  {firstName: 'John', age: 23},
  {firstName: 'Bill', age: 24}
]

Advanced Javascript Array Sort Techniques

Special Cases When Using Javascript Array Sort

• Mixed Types: When dealing with an array that contains mixed types (numbers, strings, objects), an inventive compare function is key. As 'sort()' initially converts the values to strings and uses their UTF-16 code unit values, mixing types might lead to unexpected results. Writing a comparison function that intelligently identifies types can effectively resolve this issue.
• Nested Arrays: A common, yet intricate scenario is sorting nested arrays (arrays within arrays). While the Array Sort method will attempt to sort the nested arrays based on their first element's value, if you require a different sorting criteria, a custom compare function is required.
• Sorting by Multiple Properties: If you have an array of objects where you need to sort by multiple object properties, crafting a more complex compare function is essential. This approach targets one property first, then uses additional properties in the event of a 'tie'.

Examples of Javascript Array Sort in Advanced Use Cases

// Case 1: Mixed Types
let mixedArray = [10, "20", {name:'John'} , "Zebra", "1", 200];
mixedArray.sort(function(a, b) {
  if (typeof a === 'number' && typeof b === 'number') {
    return a - b;
  }
  return a.toString().localeCompare(b.toString());
});

// Case 2: Nested Arrays
let nestedArray = [[1, 90], [90, 1], [2, 80], [80, 2]];
nestedArray.sort(function(a, b) {
  return (a[0] + a[1]) - (b[0] + b[1]);
});

// Case 3: Sorting by Multiple Properties
let students = [
  {age: 16, name: 'John'},
  {age: 15, name: 'Amy'},
  {age: 16, name: 'Bill'},
  {age: 15, name: 'Zara'}
];
students.sort(function(a, b) {
  if (a.age === b.age) {
    return a.name.localeCompare(b.name);
  }
  return a.age - b.age;
});