The String match()` Function in JavaScript – onlinecode
In this post, we will give you information about The String match() Function in JavaScript – onlinecode. Here we will give you detail about The String match() Function in JavaScript – onlinecode And how to use it also give you a demo for it if it is necessary.
JavaScript Strings have a match() method that returns an array if the string matches a given regular expression, or null otherwise.
'abc'.match(/a/); // [ 'a', index: 0, input: 'abc', groups: undefined ]
'abc'.match(/z/); // null
// Use 'match()' to check if a string matches a regexp
if (str.match(regexp) != null) {
// matches!
}match() is very similar to the RegExp test() method, which returns true if a regexp matches a given string.
/a/.test('abc'); // true
/z/.test('abc'); // falseIf all you want to do is test whether a string matches a regexp, you should use test() because test() is slightly faster.
However, match() has some helpful advanced features.
Capture Groups for The String match() Function in JavaScript
The match() function’s return value contains the regular expressions’ capture groups.
A capture group is a subsection of the regular expression in parentheses ().
For example, d is a capture group in the following.
const arr = 'There are 4 lights'.match(/(d) lights/);
arr[0]; // "4 lights", the complete match
arr[1]; // "4", the first capture groupCapture groups are useful for pulling subsections of a given regular expression result.
For example, below is how you can use capture groups to convert a date in YYYY-MM-DD format into year, month, and day.
const str = '2022-06-01';
// 4 digits, dash, 2 digits, dash, 2 digits. The 4 digits, 2 digits, 2 digits
// are capture groups.
const [year, month, day] = str.match(/(d{4})-(d{2})-(d{2})/).slice(1, 4);
year; // '2022'
month; // '06'
day; // '01'Note that capture groups do not work if you specify the g flag on your regular expression.
Practical Example: Standardizing US Telephone Numbers
There are many different ways to write a US telephone number.
All the below examples are not uncommon.
2016930123
+12016930123
+1 201-693-0123
+1 (201)-693-0123
201 693 0123Suppose you want to standardize, and always store 2016930123, but allow all the other formats?
Use the following regular expression: optional leading +1 as a capture group, and then capture groups for the area code, telephone prefix, and line number.
/^(+1s?)?(?([d]{3}))?[-. ]?([d]{3})[-. ]?([d]{4})$/Assuming there is a match, the following will convert a telephone number in any of the given formats to 2016930123
const processedTelephoneNumber = telephone.
match(/^(+1s?)?(?([d]{3}))?[-. ]?([d]{3})[-. ]?([d]{4})$/).
slice(2, 5).
join('');JavaScript Fundamentals for String match() Function in JavaScript
JavaScript is a programming language that is used to create interactive web pages. It is a client-side scripting language, which means that it runs on the user’s browser. JavaScript can be used to add animation, interactivity, and functionality to web pages.
Here are some of the fundamentals of JavaScript:
- Variables: Variables are used to store data. They are declared using the
varkeyword. - Data types: JavaScript has a variety of data types, including strings, numbers, booleans, objects, and arrays.
- Operators: Operators are used to perform operations on data.
- Control flow statements: Control flow statements allow you to control the order in which your code is executed.
- Functions: Functions are blocks of code that can be reused.
- Objects: Objects are used to store data in key-value pairs.
- Arrays: Arrays are used to store data in a sequential order.
- Events and event handlers: Events are notifications that are sent by the browser when something happens, such as when the user clicks on an element or moves the mouse over an element. Event handlers are functions that are called in response to an event.
- DOM manipulation: The Document Object Model (DOM) is a tree-like structure that represents the elements of a web page. JavaScript can be used to manipulate the DOM to change the appearance or behavior of a web page.
These are just some of the fundamentals of JavaScript. There are many other concepts that you can learn as you continue to develop your skills.
Here are some resources that you can use to learn more about JavaScript:
- Mozilla Developer Network (MDN): The MDN is a great resource for learning about JavaScript. It has a comprehensive reference guide, tutorials, and articles on a wide range of topics.
- W3Schools: W3Schools is another great resource for learning about JavaScript. It has interactive tutorials and quizzes that can help you learn the basics of the language.
- JavaScript.info: JavaScript.info is a website that provides in-depth tutorials on JavaScript. It also has a forum where you can ask questions and get help from other JavaScript developers.
I hope this helps!
Here are some additional tips for learning JavaScript:
- Start with the basics: Before you start trying to build complex applications, it’s important to learn the basics of JavaScript. This includes things like variables, data types, operators, and control flow statements.
- Practice regularly: The best way to learn JavaScript is to practice regularly. Try to find some time each day to work on JavaScript projects.
- Get help from others: If you get stuck, don’t be afraid to ask for help from others. There are many online forums and communities where you can get help from other JavaScript developers.
With a little practice, you’ll be able to learn JavaScript and start building amazing web applications.
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