Parameters
Formal Parameter
A formal parameter is a dummy variable listed in the subprogram header and used in the subprogram. In the JavaScript programming language, a function is an executable code that does a specific feat. The function parameters are the name list defined in the function. Input values are also called formal parameters or formal arguments. In JavaScript, a formal parameter is called a function parameter. The function declaration is missing valid parameters. In declaring a function, the parameters must be identifiers, not any value like numbers, strings, or objects. Declaring functions and calling functions are two separate steps. There are a few rules to declare the formal parameter in React.js, like to prevent error set, declare the parameters as the final ones, JavaScript function definition does not specify a parameter type, it does not check the input argument type and lastly, it does not check the number of input arguments (What Are the Basic Rules for JavaScript Parameters?, n.d.).​​
The following is the program-statement, which declares a default argument to the function: Thus, when no value is passed to the argument of the function it then uses the default value.
Input:
Output:
Sample Code for the formal parameter in our sample application
A formal parameter in function declaration, e is the formal parameter of the handleTimeChange function.
Actual Parameter
An actual parameter represents a value or address used in the subprogram. A JavaScript function does not perform any checking on parameter values(arguments). In JavaScript, actual parameters are called as arguments. The parameters declared in the function definition have two variants, which exist when the function is called – actual parameters or arguments. In other words, the function headers defined by the identification of the variables’ formal parameters correspond to the actual parameters that are passed to a specific function when invoked by the program.
In this case, the add function has two real parameters provided to it: A5 and C3.
Application of Parameters:
With the help of the JavaScript parameters programmers can create functions that are more flexible when processing different types of data sources. They enhance a program by making function calls, Where the functions are called with different parameters to enhance the capability of reusing the original programming. These applications help in coming up with parameters that allow for functions to be fulfilled but for inputs that are used. As conveyed in the example above, the greet function takes a name parameter in its argument and extends a greeting accordingly (JavaScript Parameter - Javatpoint, n.d.).
Sample Code for the actual parameter in our sample application
handleTimeChange function is called with the event object e being passed as an actual parameter to it.