Apply() question for javascript

Question

I study the following code to log:

console.log.apply( console, arguments );

What is the purpose of apply() here?

Why not just console.log("message", arguments)?

Answer 1

console.log("message", arguments)

calls log with two arguments, "message" and the array-like object arguments.

console.log.apply( console, arguments );

calls it with n arguments, where n is the length of the array-like object arguments. In other words, arguments is unwrapped into individual arguments. The context of the method is console. E.g.:

function foo(a, b, c)
{
  console.log.apply( console, arguments );
}
foo(1,2,3);

is roughly equivalent to:

console.log(1,2,3);

Answer 2

The apply() function calls another function with a given this value and arguments provided as an array.

The reason for an implicit func.apply(obj, args) is to make sure that within func(), this refers to obj.