JavaScript optional parameter

Note the difference between parameters and arguments: Function parameters are the names listed in the function’s definition. Function arguments are the real values passed to the function.

The parameters, in a function call, are the function’s arguments . JavaScript arguments are passed by value: The function only gets to know the values, not the argument’s locations. If a function changes an argument’s value, it does not change the parameter’s original value.

A method that contains optional parameters does not force to pass arguments at calling time . It means we call method without passing the arguments. The optional parameter contains a default value in function definition. If we do not pass optional argument value at calling time, the default value is used.

The parameters, in a function call, are the function’s arguments . JavaScript arguments are passed by value: The function only gets to know the values, not the argument’s locations. If a function changes an argument’s value, it does not change the parameter’s original value.

Optional parameters are defined at the end of the parameter list, after any required parameters . If the caller provides an argument for any one of a succession of optional parameters, it must provide arguments for all preceding optional parameters.

Optional parameters are defined at the end of the parameter list, after any required parameters . If the caller provides an argument for any one of a succession of optional parameters, it must provide arguments for all preceding optional parameters.