Question

In Javascript, you can create an object with a property name this way:

var person = { name: "Tucker" };

But also that way:

var person = { "name": "Tucker" };

Are these two equivalent? Which one is preferred?

Same goes with accessing a property:

person["name"] = "Dale";

vs.

person[name] = "Dale";

In Eloquent JavaScript, the author says that The part between the brackets can be any expression. It is converted to a string to determine the property name it refers to..

So, I guess directly putting a string between the brackets would be considered best practice.

Last but not least, properties can be accesses by using the dot notation:

person.name = "Dale";

if the property is a valid variable name. Does it actually makes sense to use this notation over the seemingly more flexible bracket notation?

Answer 1

These are the same, the only difference is that if your key is reserved keyword, you need the quotes:

var person = { name: "Tucker" };
var person = { "name": "Tucker" };
var person = { "for": "Tucker" }; //Need quotes here

When accessing, the same rules apply

person["name"] = "Dale"; //Sets the person object's name attribute to "Dale", the brackets are needed for variables or expressions.
person.name = "Dale";    //Same operation, different syntax
person[name] = "Dale";   //Sets the attribute equivalent to the value of the variable name, not necessarily "name"

Does it actually makes sense to use this notation over the seemingly more flexible bracket notation?

It is entirely up to you, or whoever decides your project’s coding standards. The dot notation is simpler and reminiscent of Java/C/C++ (if you’re into that sort of thing) and brackets, as you noted, are more flexible.