How to use the JavaScript startsWith() Method

Summary: This article will show you how to use the javascript startsWith() method. This method is useful for checking if a string starts with a certain value. It can be used in many different scenarios, such as checking if an email address starts with “johndoe@gmail.” A common use of this function is when creating form validation that requires input values starting with letters or numbers (e.g., name fields).

Javascript startwith() syntax

Summary: javascript startswith Javascript startswith is a javascript function that checks if the given string starts with value.

Syntax:

string.startsWith(substring, [position]);

Parameters or Arguments :

substring: the substring to search for.

position: The index at which to start looking, starting from either 0 or string.length – position (inclusive). Defaults to 0 if not given

Returns true when it starts with value and false otherwise.

What is the Javascript startsWith() method?

The javascript startswith() function is a boolean that indicates if the string starts with a value. It returns either true or false based on whether it begins with the given character sequence, and can be used in many different scenarios such as checking if an email address starts with “johndoe@gmail.”

What are some common uses of javascript startsWith()?

You can use javascript startswith to check if a value starts with letters or numbers (e.g., name fields).

Two other examples are checking for words and phrases in text input, such as “A string that is starting” vs. “A string that isn’t.”

Example 1:

var email = "johndoe@gmail.";

if (email.startsWWith("johndoe")) { 

alert('Yes, that is my email address.');} 

else { alert ('no this isn't my email') }

The javascript startsWith() function also comes in handy with string manipulations, such as removing text, adding a prefix or suffix to the string, and translating strings.

Example 2:

var email = "johndoe@gmail."; 

if (email.startsWith("johndoe")) 

{ // do something} 

else { alert ('no this isn't my email') } 

NOTE:

-This method is case sensitive

-This method can only be used to find values that start with the value you pass in.

Advantage and disadvantage of using Javascript startsWith()

-This function can’t be found in javascript’s string object, so it is a little more efficient to use this method.

The disadvantage of using Javascript startsWith()

-The javascript startsWith() method only works with strings that start with the value you pass in. This means if your string doesn’t match what you’re looking for, javascript will return false.

-The javascript startsWith() method is case sensitive so you have to be careful of this when using it in your code and the javascript startswith() function can’t find values that don’t match what’s being searched for. This means if your string doesn’t start with a value you specified javascript will return false.

-The javascript startsWith() method uses a regex to search for the value you’re looking for in your string, which means it’s case sensitive and might not work with complex values that have more than one word before or after what you are looking for.

-If startsWith is used improperly, javascript runs into errors and might not work properly, which can be a major pain to debug.

-The javascript startsWith() method is very useful if you need to check whether or not your string has certain text in it at the beginning of its value.

Conclusion:

JavaScript has a startsWith() method that you can use to determine if the specified string starts with the given substring. You need to supply both arguments for this function, which is an array and a string. The last argument indicates whether or not cases should be considered when determining if they match (true) or only letter order matters (false). If no third parameter is supplied then it defaults to false. After checking out these examples of how the startsWith() works in different situations, you may want to try using it yourself!

Also Read : Inserting an Element Using insertbefore JavaScript

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