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JAVASCRIPT
Strings in JavaScript are immutable, which means that once a string is created, it cannot be changed. However, you can manipulate strings using various string methods to create new strings based on existing ones. Some common string methods include concat()
, toUpperCase()
, toLowerCase()
, substring()
, split()
, and many more.
For example:
JavaScript provides a rich set of features and methods to work with strings, making it easy to manipulate and process textual data within your programs.
Using double quotes:
Using backticks (also known as template literals):
All three declarations are valid and will create a string variable. You can choose the style that you find most readable or convenient for your specific use case.
It’s worth noting that template literals (backticks) have additional capabilities compared to single or double quotes. They allow for string interpolation, which means you can embed expressions or variables directly within the string using the ${}
syntax. For example:
Using string concatenation, you can combine multiple strings or string variables:
Remember that strings are immutable, meaning their values cannot be changed once assigned. However, you can create new strings by manipulating existing ones using various string methods.
In the example above, the + operator is used to concatenate the strings str1
, ", "
, str2
, and "!"
together, resulting in the final string "Hello, world!"
.
2. Using the concat()
method:
In this case, the concat()
method is called on str1
and passed ", "
, str2
, and "!"
as arguments. The method combines all the strings in the specified order and returns the concatenated string.
Both approaches achieve the same result, so you can choose the one that suits your coding style and preference. The concatenation operator (+) is more commonly used, while the concat()
method can be useful when concatenating multiple strings or when the order of concatenation needs to be more dynamic.
In the example above, the original greeting
string remains unchanged even though it appears as if we appended ", world!"
to it. In reality, the +
operator creates a new string (modifiedGreeting
) by concatenating the original greeting
with ", world!"
. The original string remains intact and unaffected.
String immutability has important implications when working with strings in JavaScript. It means you cannot directly modify individual characters or substrings within a string. Instead, you need to create new strings by combining existing ones or using string manipulation methods.
For example, to convert a string to uppercase, you cannot modify the original string. Instead, you create a new string with the uppercase representation:
The original text
remains unchanged, and a new string uppercaseText
is created with the modified content.
String immutability is an important concept in JavaScript and ensures the stability and predictability of string values. It also allows for efficient memory management and enables certain optimizations in the JavaScript engine.
In the example above, the length
property is accessed on the message
string using dot notation (message.length
). The value of length
will be the number of characters in the string, which is 13 in this case.
It’s important to note that the length
property is a property, not a method, so it doesn’t require parentheses when accessing it.
The length
property is commonly used to perform operations or checks based on the length of a string. For example, you can use it in loops to iterate over each character in a string or use it to check if a string meets a certain length requirement.
In the example above, the length
property is used to check if the username
string is longer than 10 characters and display an appropriate message based on the result.
By utilizing the length
property, you can easily determine the size of a string and use it in various scenarios within your JavaScript code.




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