Javascript substring offers a range of functions and methods. It is a popular programming language used in web development. It makes it easier to manipulate data and create dynamic web pages.
One of these functions is the Javascript substring, which allows developers to extract a specific string section.
In this article, we’ll explore the basics of these substring functions. Besides, we look at how it works and what its syntax is.
Furthermore, we study how it can be used in practical web development scenarios.
What Is a Substring in Javascript?
A substring in Javascript is a sequence of characters part of a larger string. Using the substring function, developers can extract a specific string section. Based on the starting and ending indexes.
Example
If we have a string “Hello World!”, we can use the substring function to extract the word “World.”
We can do this by specifying the substring’s starting and ending index positions.
Syntax of the Javascript substring function
The substring function in Javascript has a simple syntax that consists of two parameters:
- The starting index
- The ending index
The syntax is as follows:
string.substring(start, end)
In this syntax, the start parameter is the index position at which the substring begins. However, the end parameter is the index position at which the substring ends.
The End Parameter is Optional
It’s important to note that the end parameter is optional. If not provided, the substring function will extract all the characters from the start index position to the end of the string.
Example
Here’s an example of how the substring function works:
let str = “Hello World!”;
let str = str.substring(6, 11);
console.log(substr); // Output: “World”
In this example, we create a string “Hello World!” and then use the substring function to extract the substring “World.”
The start parameter is 6. It is the index position of the letter “W” in the string. Besides, the end parameter is 11, which is the index position of the letter “d.”
If we omit the end parameter, the substring function will extract all the characters from the start index position to the end of the string:
Example
let str = “Hello World!”;
let substr = str.substring(6);
console.log(substr); // Output: “World!”
In this example, we only provide the start parameter, 6. The substring function then extracts all the characters from the 6th index position to the end of the string.
Common Use Cases for the Javascript Substring Function
The Javascript substring function can be used in various web development scenarios. Here are some simple use cases:
Extracting part of a URL
When building web applications, extracting specific parts of a URL is often necessary.
For example, if we have a URL like “https://www.example.com/blog/article/1234”, we may want to extract the article ID (in this case, “1234”).
By using the substring function, we can easily extract the article ID from the URL:
let url = “https://www.example.com/blog/article/1234”;
let article = url.substring(URL.lastIndexOf(“/”) + 1);
console.log(article); // Output: “1234”
In this example, we use the lastIndexOf function to find the index position of the last forward slash in the URL.
We then add 1 to this index position to get the starting index position of the article ID. Finally, we use the substring function to extract the article ID from the URL.
Bottom Line
In short, JavaScript substring is a method used to extract a portion of a string. It takes two parameters: the starting index and the ending index.
The starting index is inclusive, and the ending index is exclusive. It means the character at the ending index is not included in the returned substring.
If the ending index is omitted, the substring will go to the end of the string. In addition, the substring method can be used to manipulate strings in various ways, such as:
- Removing or replacing particular character
- Extracting specific information from a string
- Formatting text in a desired way
