JavaScript Program to Set a Default Parameter Value For a Function

The syntax to set the default parameter value for a function is:

function functionName(param1=default1, param2=default2, ...) {
    // function body
}

Example 1: Set Default Parameter Value For a Function

Output

20
12
8

In the above example, the default value of x is 3 and the default value of y is 5.

• sum(5, 15) - When both arguments are passed, x takes 5 and y takes 15.
• sum(7) - When 7 is passed to the sum() function, x takes 7 and y takes the default value 5.
• sum() - When no argument is passed to the sum() function, x takes the default value 3 and y takes the default value 5.

Example 2: Using Previous Parameter in Another Parameter

Output

22
32

You can also pass a parameter as the default value for another parameter.

In the above program,

• When 10 is passed to the calculate() function, x becomes 10, and y becomes 12 (the sum function returns 22).
• When no value is passed to the calculate() function, x becomes 15, and y becomes 17 (the sum function returns 32).