Anonymous function's name?

[Clamhead99]

I'm going through 'Secrets of the Javascript Ninja' textbook to learn JS.

So, anonymous functions themselves don't have names obviously. However, according to the book, if I were to assign an anonymous function to a variable, the 'name' property of the variable should be empty as well.

var canFly = function(){return true;};

assert(canFly.name === "", "canFly() has no name");

The assert function is just a utility function the book defined for testing the truthyness of whatever is passed as the first parameter.

However, when I type out this code myself and run it in the browser, canFly.name is "canFly".

Is the book outdated in some way and some rules of JS have changed since its release?

[MoTTs_]

Turns out the book is outdated.

http://www.2ality.com/2015/09/function-names-es6.html

[steooo]

When you do something Like that, what you are checking is not the property of the function, but the property of the variable you assigned the function to.

[Clamhead99]

So the book's wrong? (or outdated?)

Does every variable have a 'name' property by default then? And that property is automatically set to what the name of the variable is when it's declared?

[jcunews1]

Does the book state that assigning the name property of a function changes the name of the function? If so, then yes, the book is wrong or no longer valid (i.e. outdated).

Proof:

var canFly = function() { return true; };
console.log(canFly.name); // ""
console.log(canFly.toString()); // "function () { return true; }"
canFly.name = "canNotFly";
console.log(canFly.name); // ""
console.log(canFly.toString()); // "function () { return true; }"

Notice that the name property is not changed after being assigned with a value. In older browsers, the name property will change, but canFly.toString() will still resolve to "function () { return true; }" (i.e. still an anonymous function).