Introduction of JavaScript
Did you know that 98.9% of websites use JavaScript in 2025? But people still get confused between let, var, and const. Yes, it’s true, around 98.9% of websites will use JavaScript as their main programming language in 2025. JavaScript has become one of the most popular coding languages this year. In this blog, I will be explaining the purpose of the 3 different types of variable declarations.
Even though JS is very popular, it’s also very complex to understand. One of the main complexities in JavaScript is the variable declaration. There are 3 different types of variable declarations, Let, Var, and Const.
What is the purpose of Var?
Unlike Let, Var is accessible throughout the entire function, which means it can be used outside the curly braces. Also, the variable can be changed or re-assigned in Var. Even when a variable is declared using Var inside a block, it does not create a block-level scope which means that Var can be used outside of a block.
Think about this, a block has been locked inside a function, it cannot escape. Unless it’s a Var. All in all, a var is a type of variable declaration that can be used outside a function block. Also, the name of Var can be re-assigned. For example, if it’s “var name1”, it can be changed to “name2” underneath the original Var. Also, if you declare a variable inside a block, it can be used anywhere even outside the block.
What is Const and what is it used for?
Const which means “constant” is one of the 3 variable declarations in JavaScript, it is a special way to declare a variable. In Let and Var, you could re-assign the variable, but that is not the case with Const. When you declare a variable using Const, it remains constant which means that it cannot be changed.
Const, which also means “constant” is a type of variable that is a bit different from “Let” and “Var”. So with Const, you are NOT able to change the declaration of the variable. For example, if you write “Const name1”, you CAN’T change the declared variable. You have to change the variable from the original. Which means that you can’t change the name of it. This type of variable declaration is useful when you don’t want to accidentally change the name of the variable.
Even though you can’t reassign the constant variable, you can still modify the codes inside the variable. This means that you are still able to change what the variable does even though you can’t change the name of the variable.
If you are doing a project in JS and if a code is very important, then you can use the Const variable to make sure that you do not change the code by accident. But also keep in mind that you are still able to change the array and functions inside the Const variable.
Conclusion
There are 3 types of variable declarations in JavaScript and each of them are unique in their way. They can be used for different purposes and have different benefits for each. Each of the variable declarations is unique in its way and they each have their purposes. Make sure you know which variables are used when and for what purpose. Const cannot be reassigned, even though the functions and arrays can be. Let can be reassigned but they can’t be used outside of the function block. Var can be reassigned and also be used outside of the block and function.
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