Javascript String Contains

Michael Zippo 04.11.2021

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You can check whether a JavaScript string contains a character or a phrase using the include (), indexOf () method, or a regular expression. include () is the most common method used to check if a string contains a letter or a series of letters and was designed especially for this purpose.

Checking whether a string contains a substring is a common thing to do in a programming language. For example, suppose you are creating an online game . You can check if a name of user contains a phrase prohibited to make sure that all names of users are tailored to your game.

string JavaScript contains

There are three methods to check if a JavaScript string contains a character or a sequence of characters: ...

includes ()
indexOf ()
The regular expressions (regex)

In this tutorial, we will discuss methods you can use to check if one JavaScript string contains another string using these three approaches

The string contains JavaScript. include ()

the JavaScript include method () , introduced in ES6, determines whether a string contains the characters passed to the method. If the string contains some characters, the method returns "true".

If the specified string does not contain the characters you are looking for, include () will return "false"

The syntax of the include () method is:

The value of "string" refers to the characters through which we will search. "Speech" refers to the characters we are looking for

Here is an example of include () in action:

Our code returns:. The word example is in the string

In the first two lines we declare two JavaScript variables . The first variable is the string we want to do the search. The second is the substring we want to find in our original string . In other words, we will look to see if the first variable contains the contents of the second variable

Next, we use an if statement to evaluate whether the "example" variable contains the contents of the variable "ourSubstring"

If. "example & rdquo; contains the word "example", returns our TRUE. this means that the console.log () statement is executed in the body of our "if". otherwise, our "else statement" is executed.

understands () makes a distinguishing case, so if we changed the case of our substring, it would return "false". method

the second argument includes ()

the include () allows you to specify a second argument. This second argument is the index number at which include () should start looking for your substring. the first character would have an index of "0", the second "1", and so on. in fact, the re-indexing of lists from scratch

Or check if the word "example". Appears after the index position 7 in our chain:

The include method returns () the index position where our string begins. Our code declarations "The word example is not in the string." " Although our string includes the word" example ", the word appears before the value of the subscript" 7 ", which is the space between" example " and

JavaScript checks if the string contains" String! ": IndexOf ()

The process, such as include () JavaScript indexOf (), checks if one character string includes another chain. What is different is the output of these two functions

When we use the include () method, the method returns a boolean. True or false. indexOf () returns the starting index position of the substring. Or, if the string does not include the substring, we get "-1".

Tokens a look at the syntax of this method:

As in our include () example, "string" refers to the value we are looking for. "Word" is the expression or character we are looking for

Here is an example of indexOf () in JavaScript.

Our code returns: The word is Example in the string. We used an "if" like we did in our last example. This declaration displays a message from the same party to the console depending on whether our string contains a substring.

We check if the indexOf () method does not return -1. In this case, the "other‚" instruction is executed. -1 indicates that our string was not found. Otherwise, the code inside our "if" is executed

We use indexOf () on a string that does not contain a substring.

Our code returns -1 because our substring cannot be found

indexOf (), since the process includes (), is case sensitive . If we want our search to start at a certain index value, we can use another argument:

The string contains JavaScript. Regex

We can also use JavaScript regular expressions -o regex - to check if a string contains a substring. Regex can be extremely useful because of its flexibility: you have a lot of control over what you’re looking for and

can use the RegExp.test () method to check if a string contains a substring. Here is an example: "Example string"

Regex is powerful. The downside to regex is that it can be slower to run depending on the rules you use. The more statements you add to your regex rules, the longer your search will take.

If you are doing a simple search and don’t need advanced string functions, using include () or indexOf () might be a better approach. The .test () method is not recommended for beginners who have not yet learned about Regex

If you are looking to learn more. At about regex and test your regex, see RegExr .

Conclusion

In this tutorial, we discussed the basics of strings in JavaScript. Next, we discussed three ways you can check if a string contains a substring in JavaScript: using include (), indexOf () and regex

include method () is probably the most common way to check. if a string contains a substring. Indeed, the method name is literal. It is clear that Include () allows you to search for a string within another string.

Want to learn more about JavaScript? We’ve got you covered . Check out our How to Learn JavaScript for expert advice on learning. You will also find a list of the best learning resources for you. der to improve your knowledge.

We hope this article has helped you to resolve the problem. Apart from Javascript String Contains, check other ast Python module-related topics.