Learn ECMAScript - Second Edition

Using a destructuring assignment as a parameter

We can also use an array destructuring expression as the function parameter for extracting the values of an iterable object, passed as an argument into the function parameters. The following example demonstrates this:

   function myFunction([a, b, c = 3]) {
     console.log(a, b, c); //Output "1 2 3"
   }
   myFunction([1, 2]);

Earlier in this chapter, we saw that if we pass undefined as an argument to a function call, then JavaScript checks for the default parameter value. So, we can provide a default array here too, which will be used if the argument is undefined. The following example demonstrates this:

   function myFunction([a, b, c = 3] = [1, 2, 3]) {
     console.log(a, b, c);  //Output "1 2 3"
   } myFunction(undefined); ...