https://stackoverflow.com › questions › 411352

Sometimes you want undefined as a possible argument but you still have situations where the argument may not be passed. In that case you can use arguments.length to check how many arguments were passed.

https://stackoverflow.com › questions › 4116608

You can access the arguments passed to any JavaScript function via the magic arguments object, which behaves similarly to an array. Using arguments your function would look like: var print_names = function() { for (var i=0; i<arguments.length; i++) console.log(arguments[i]); }

https://stackoverflow.com › questions › 39953067

You have to understand the difference between undefined and undeclared variables. At least you would do: var x; //undefined until assignment; isUndefined(x); // returns true;

https://www.w3schools.com › js › js_function_parameters.asp

If a function is called with missing arguments (less than declared), the missing values are set to undefined. Sometimes this is acceptable, but sometimes it is better to assign a default value to the parameter:

https://developer.mozilla.org › ... › Web › JavaScript › Reference › Functions › Default_parameters

In JavaScript, function parameters default to undefined. However, it's often useful to set a different default value. This is where default parameters can help. In the following example, if no value is provided for b when multiply is called, b's value would be undefined when evaluating a * b and multiply would return NaN.

https://developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Functions › arguments

The arguments object is a local variable available within all non-arrow functions. You can refer to a function's arguments inside that function by using its arguments object. It has entries for each argument the function was called with, with the first entry's index at 0. For example, if a function is passed 3 arguments, you can ...

https://www.javascripttutorial.net › javascript-undefined

JavaScript uses the undefined value in the following situations. 1) Accessing an uninitialized variable. When you declare a variable and don’t initialize it to a value, the variable will have a value of undefined. For example: let counter; console.log(counter); // undefined Code language: JavaScript (javascript)

https://www.javascripttutorial.net › javascript-default-parameters

Setting JavaScript default parameters for a function. In JavaScript, a parameter has a default value of undefined. It means that if you don’t pass the arguments into the function, its parameters will have the default values of undefined. See the following example: function say (message) { console.log(message); } say(); // undefined Code ...