21. Here are some reasons for vars in Scala: Scala is a multi-paradigm language, it encourages functional programming, but it leaves the choice to the programmer. Comptibility: Many Java APIs expose mutable variables. Performance: Sometimes using a var gives you the best possible performance. When people say that everything can be done without 1. T his Story is from the Kotlin- Series, In which we will learn What is the actual difference between val and var. Basically, val and var both are used to declare a variable. var is like a Thus, variables declared using let minimize the possibilities of runtime errors, as the compiler give compile-time errors. This increases the code readability and maintainability. Const. Variables can be declared using const similar to var or let declarations. The const makes a variable a constant where its value cannot be changed. The differences between var, let, and const variable declaration in JavaScript include: Variables declared with var and const are scoped to the immediate function body. Variables declared with the var keyword are hoisted. Hoisting means that the variable can be accessed in their enclosing scope even before they are declared. Calculate cube of each element with the help of map. function cube (n) {. return n*n*n; } var arr=new Array (1,2,3,4) var newArr=arr.map (cube); console.log (newArr) // Output : [1,8,27,64] In the above example, a function called “cube” is created and then is passed as a callback function into map (). Consider the below example, where er 01BJUrn. This can actually be boiled down to a couple of good practices: const is preferred to let, which is preferred to var. Avoid using var. let is preferred to const when it's known that the value it points to will change over time. const is great for global, constant values. Kotlin constants are used to define a variable that has a constant value. The const keyword is used to define a constant variable. The const keyword can only be used with the val keyword and not with the var keyword. const val empName = "employee_1" println (empName) employee_1. If we try to declare a constant with var keyword, we will get Differences between let and var. Called constants also. Called variables also. These are immutable. These are mutable. We use the let keyword to define a constant. We use the var keyword to define a variable. The let keyword cannot be applied to lazy properties. The var keyword is required for lazy properties. Difference between Let vs Var vs Const Variable Scope. The scope or visibility of the variable is the major difference between these keywords. var is function scoped. The variables declared using var inside the function are available only within that function. If we declare them outside the function, then they are available everywhere i.e. they Note: In case of global scope, both var and let will behave in the same way. For example, var a = 5; // 5. The variable a will be global scoped and can be accessed anywhere in the program. let a = 5; // 5. The variable a will be global scoped and can be accessed anywhere in the program.

difference between var and val