JavaScript has two keywords for declaring variables: “let” and “const”. Both keywords have similar functionality, but there are some differences between them that are important to understand.

“Let” allows you to declare a variable whose value can be changed later in the code. For example, let’s say you want to declare a variable named “x” and assign it a value of 5. You would use the following code:

let x = 5;

Later in the code, you can change the value of “x” by simply assigning a new value to it:

x = 10;

“Const” is similar to “let”, but it declares a variable that cannot be reassigned. If you try to change the value of a “const” variable, you will get an error. For example, the following code would result in an error:

const y = 5; y = 10; // Error: Assignment to constant variable.

It’s important to note that the value of a “const” variable can still be changed if it’s an object or an array. For example:

const z = {}; z.name = 'John'; // This is allowed. z = {}; // Error: Assignment to constant variable.

So, when should you use “let” and when should you use “const”? Here are a few guidelines:

  • Use “const” when you want to declare a variable that will never change.
  • Use “let” when you want to declare a variable that will change.
  • Use “const” when you want to make sure that a variable can’t be reassigned.
  • Use “let” when you want to declare a variable in a loop, as the value of the variable needs to change with each iteration.

In conclusion, the choice between “let” and “const” depends on the specific use case and the intended behavior of the variable. It’s important to understand the differences between these two keywords, as using the wrong keyword can lead to unexpected results or errors in your code. By using “const” when appropriate and “let” when needed, you can write cleaner and more maintainable code.

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