how assign value to parameter in the function javascript code example

Example 1: javascript function variable arguments

function foo() {
  for (var i = 0; i < arguments.length; i++) {
    console.log(arguments[i]);
  }
}

foo(1,2,3);
//1
//2
//3

Example 2: variable defaults javascript es6

let variableToSet = checkedValue || defaultValue;