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String Manipulation with JavaScript

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Search Methods

5:24 with Reggie Williams

Applications that require users to signup and sign in often have unique constraint requirements for passwords and other form fields. Password fields can require verification that certain characters are included in a password string. You may need to determine if an email address ends with a specific string like .edu. JavaScript provides strings with methods that allow us to accomplish these tasks and more.

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    Applications that require users to sign up and sign in often 0:00
    have unique constraint requirements for passwords and other form fields. 0:03
    Password fields can require verification that certain characters are included in 0:10
    a password string. 0:15
    You may need to determine if an email address ends with a specific 0:17
    string like dot edu. 0:22
    This small piece of a larger string is called a substring. 0:24
    JavaScript provides strings with multiple options for searching for substrings. 0:29
    The first method we'll explore is indexOf. 0:35
    The indexOf method returns the position of the first occurrence 0:38
    of a specified value in a string. 0:43
    If the substring is present, the method returns the index where it occurs. 0:47
    If the substring is not present, the method returns the value -1. 0:53
    Let's try this out in the workspace associated with this video. 1:00
    Open up a preview of the index.html 1:05
    file associated with this project by clicking the eye icon. 1:08
    For this step, we'll be working with the code in the search.js file. 1:15
    There, we have a string with the value team. 1:21
    In the console of our preview, let's run the indexOf method on index string. 1:25
    We'll pass it a value i to see where i occurs in the spring. 1:41
    We get -1 because there's no i in team. 1:47
    Now let's try to find the index of tree in our school variable that stores 1:51
    the value treehouse. 1:56
    Because the substring starts at the beginning of the string, 0 is returned. 2:11
    Strings also have a method called lastIndexOf. 2:17
    Can you guess what this method does? 2:20
    LastIndexOf searches for 2:23
    a substring starting from the strings end instead of the first character. 2:25
    For example, 2:30
    school.indexOf("e") returns 2. 2:34
    But school.last indexOf("e"), 2:43
    Returns 8, because the e at the eighth index position is 2:55
    the first e from the end of the string. 3:00
    Let's clear up the console before we go any further. 3:04
    IndexOf tells us where a substring is, but 3:08
    sometimes we only want to know if a substring is present. 3:11
    For this, we can use the handy includes method. 3:16
    Includes takes a search string and an optional index to start searching. 3:20
    It returns true if the search string is present and false if not. 3:27
    Let's replace indexOf in one of our previous examples with includes. 3:32
    We'll try school.includes("tree"). 3:40
    And we get the value true. 3:50
    We can use the starts with and ends with methods to check for 3:53
    substrings at either the start or end of strings. 3:58
    We'll clear the console again. 4:02
    In our search.js, we have a variable named childrensStory that stores a value, 4:08
    Once upon a time not long ago, and ends with the end. 4:15
    For practice, we'll write a program that checks if strings meant 4:21
    to be fairy tales start with the substring, Once upon a time. 4:26
    We'll take our childrensStory variable, use the startsWith method. 4:31
    And pass it the value once upon a time. 4:40
    We get a value of true. 4:51
    Now let's check that the story ends with the proper, the end. 4:53
    Again, we'll use our childrensStory variable. 4:58
    EndsWith passing it a value of the end. 5:04
    And we get true again. 5:12
    In the next video, I'll share a set of methods you can use when you want to 5:14
    modify a string value, and return a new object with that value. 5:18

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