How do you pass an optional parameter?

Square brackets [] are used to specify optional, positional parameters in Dart. readFile(String name, [String mode, String charset = ‘utf-8’]) { // … } For such declaration name is always required while mode and charset are optional.

Dart Constructor using Square brackets : Positional optional parameters. You can wrap one or more parameters in square brackets [ ] to make them as optional positional parameters.

By Params Keyword : You can implement optional parameters by using the params keyword. It allows you to pass any variable number of parameters to a method. But you can use the params keyword for only one parameter and that parameter is the last parameter of the method.

Named optional parameters You can call getHttpUrl with or without the third parameter. You must use the parameter name when calling the function. You can specify multiple named parameters for a function: getHttpUrl(String server, String path, {int port = 80, int numRetries = 3}) { // … } 21 Eyl 2020