JavaScript functions can take parameters, which are variables that are passed into the function. Parameters are used to customize the output of a function and can be used to make a function more versatile. This tutorial will teach you how to use parameters in JavaScript functions, how to define them, and how to pass them into a function.
Function Parameters
Function parameters are the variables that are used as arguments when calling a function. They are used to pass data into the function and allow the function to process it. Function parameters can be passed by value or by reference. When a parameter is passed by value, the function creates a copy of the parameter and uses that copy to process the data. When a parameter is passed by reference, the function uses the actual parameter in the function and any changes made to the parameter will be reflected in the original parameter. Function parameters are declared inside the parentheses of the function declaration. The parameters are separated by commas and each parameter must have a unique name. The following example shows a function declaration with two parameters:
function add(x, y) {
return x + y;
}
In this example, the function declaration has two parameters, “x” and “y”. When this function is called, two arguments must be passed in order to invoke the function. The arguments are placed in the same order as the parameters in the function declaration.
let result = add(10, 20);
console.log(result);
In this example, the arguments “10” and “20” are passed to the function. The “x” parameter is assigned the value of “10” and the “y” parameter is assigned the value of “20”. The function can then use these values to perform its calculations. It is also possible to pass a variable as an argument to a function. In this case, the value of the variable will be passed to the function. For example:
let a = 10;
let result = add(a, 20);
console.log(result);
In this example, the variable “a” is passed to the function as an argument. The value of the variable “a” is then assigned to the parameter “x”. The function can then use the value of “x” to perform its calculations. It is also possible to pass multiple variables as arguments to a function. In this case, the values of the variables will be passed to the function. For example:
let a = 10;
let b = 20;
let result = add(a, b);
console.log(result);
In this example, the variables “a” and “b” are passed to the function as arguments. The values of the variables “a” and “b” are then assigned to the parameters “x” and “y” respectively. The function can then use these values to perform its calculations. It is also possible to pass an array as an argument to a function. In this case, the values in the array will be passed to the function. For example:
let arr = [10, 20];
let result = add(arr[0], arr[1]);
console.log(result);
In this example, the array “arr” is passed to the function as an argument. The values in the array “arr” are then assigned to the parameters “x” and “y” respectively. The function can then use these values to perform its calculations. It is also possible to pass an object as an argument to a function. In this case, the properties of the object will be passed to the function. For example:
let obj = {
x: 10,
y: 20
};
let result = add(obj.x, obj.y);
console.log(result);
In this example, the object “obj” is passed to the function as an argument. The properties of the object “obj” are then assigned to the parameters “x” and “y” respectively. The function can then use these values to perform its calculations.