Nothing Special   »   [go: up one dir, main page]
Scribd Logo
Upload

Welcome to Scribd!

  • 12 views

    Sorting Arrays

    Uploaded by

    crazyscientist996
    This document discusses sorting arrays in JavaScript. It begins by showing an unsorted array and explaining that the array.sort() method can be used to sort it. However, this method does not work properly for arrays of objects by default. The document then demonstrates how to pass a comparison function to the sort method to customize the sorting for arrays of objects based on a specific property, like name. It also notes that the sort is case sensitive by default, and provides a solution to make it case insensitive.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd

    Sorting Arrays

    Uploaded by

    crazyscientist996
    12 views11 pages
    This document discusses sorting arrays in JavaScript. It begins by showing an unsorted array and explaining that the array.sort() method can be used to sort it. However, this method does not work properly for arrays of objects by default. The document then demonstrates how to pass a comparison function to the sort method to customize the sorting for arrays of objects based on a specific property, like name. It also notes that the sort is case sensitive by default, and provides a solution to make it case insensitive.

    Original Description:

    Original Title

    11. Sorting Arrays

    Copyright

    © © All Rights Reserved

    Available Formats

    PPTX, PDF, TXT or read online from Scribd

    Did you find this document useful?

    Is this content inappropriate?

    This document discusses sorting arrays in JavaScript. It begins by showing an unsorted array and explaining that the array.sort() method can be used to sort it. However, this method does not work properly for arrays of objects by default. The document then demonstrates how to pass a comparison function to the sort method to customize the sorting for arrays of objects based on a specific property, like name. It also notes that the sort is case sensitive by default, and provides a solution to make it case insensitive.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    12 views11 pages

    Sorting Arrays

    Uploaded by

    crazyscientist996
    This document discusses sorting arrays in JavaScript. It begins by showing an unsorted array and explaining that the array.sort() method can be used to sort it. However, this method does not work properly for arrays of objects by default. The document then demonstrates how to pass a comparison function to the sort method to customize the sorting for arrays of objects based on a specific property, like name. It also notes that the sort is case sensitive by default, and provides a solution to make it case insensitive.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    of 11

    Sorting

    Arrays
    Sorting arrays
    Here we have a numbers array.

    Until now, we have only dealt with sorted arrays, in real life however, arrays often come
    unsorted.

    Here we have changed the order of the numbers array.

    Let’s look at how to sort this.


    The array.sort()
    method
    We have access to a sort
    method, and what this method
    does, is that it converts each
    element into a string, then sorts
    the elements in the array.

    When we log the array to the


    console, it will display the
    sorted array.
    reverse()
    Another method often used with
    the sort method, is the
    array.reverse() method.

    This method reverses the order of


    elements in an array.

    Here we log the result of reversing


    the sorted array, which displays the
    numbers in descending order.
    array.sort()
    But, if you have an array of objects, the
    array.sort() method does not work by
    default, so we have make some
    This method makes sorting arrays of additions to this to make it work.
    numbers or strings easy.
    Sorting objects
    Here we have an array called courses,
    filled with course objects, and each course
    object has name and id properties.

    We want to sort the courses by name, so


    that JavaScript comes before Node.js

    Here we try to use the sort method, but, as


    the console shows, this does not work.

    How can we fix this problem?


    array.sort()
    The sort method accepts an optional argument, and this
    arguments is a function that is used for comparison.

    What the sort method does, is it takes two objects in the


    array (which we will call a and b), and it compares them.

    If they are in the right order, it will skip to the next two
    elements, otherwise it will rearrange the elements.
    Sorting objects
    To sort the courses by name, we pass in a function for comparison.

    This functions takes two parameters, which we will call a and b.

    In this function, if a is less than b, we return -1, if a is greater than b, then


    we return 1, and if they are equal, we should return 0.

    * Note that we don’t use an else-if statement.

    This is because the first condition is true, the return keyword will break out
    of the function, so control flow won’t reach the second if statement.

    This means there is no need for the else keyword, so we leave it out to make
    our code cleaner.
    Case Sensitivity
    If we change the J in JavaScript to a
    lowercase j, we see that Node.js appears
    first.

    Why does this happen?

    Each character in a computer is internally


    represented using a number
    ASCII Table
    If you Google search for ascii table, this
    table will show up.

    Ascii stands for American Standard Code


    for Information Interchange.

    In this table you can see the numeric


    representation of each character.

    Since lowercase j is 106, and uppercase N


    is 78, we can see 78 is less than 106, that's
    why Node came first.
    Case Sensitivity
    To solve this problem we should exclude case
    sensitivity when comparing these names.

    To do this, we can declare 2 constants, then it it to


    name and apply either the toUpperCase or
    toLowerCase method.

    So whatever the name of the first course is, we're


    going to convert it to uppercase or lowercase, and
    we're going to do the same with the second course.

    Now the sort algorithm works properly.

    You might also like