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JavaScript JavaScript Loops, Arrays and Objects Tracking Data Using Objects The Object Literal

Posted by A X
A X
12,842 Points

Having Difficulty Understanding Object Literals in JS

Hi TH Community, Just diving into Dave's JS course on Object Literals, and he presented literals as an object that you can store information about your object into. Maybe it's because I've taken some of the SQL classes, but how is an object literal any different than creating a small database? Meaning that you're putting potentially a bunch of information in about 1 object...I liken it to describing all the parts that make up the human body and calling it an instance of a human object...but it's just information...so can someone describe simply to me what exactly an Object Literal is?

Aaron Martone
Aaron Martone
3,290 Points
Aaron Martone
Aaron Martone
3,290 Points

As for object instantiation (making an instance of an object), the great thing you'll learn about JS is that, when done well, you can define properties on the object that are unique (like a name or age of a Person object), but then you can use the prototype to add common functions or properties. Defining them on the prototype means they are inherited, but not defined directly on the object. This saves memory. Think of it this way:

var Person1 = { name: 'John", age: 32, walk: function() { /* I am walking... */ }};

As we make more and more Persons with different names/ages, the walk function defined on it is duplicated, wasting memory. Down the line, when you want to define a shared method, you do it like so:

Person.prototype.walk = function() { /* I am walking... */ };

And now, each Person object you create will have its own name and age property, but a walk function isn't defined ON the object. But due to JavaScript's prototypal nature, it will look up it's prototype chain when you ask for a method/property that isn't defined directly on the object. And using the aforementioned method, it will find the walk method and allow a Person object to use it.

There's lots of great stuff about JS. We're all getting better at it step by step.

john larson
john larson
16,594 Points

nekilof, I 'm wondering about SQL. I met a programmer that only works with SQL (and a php framework to manage it). He seemed to be gainfully employed and quite happy with his position. What's your impression of it?

1 Answer

Aaron Martone
Aaron Martone
3,290 Points
Aaron Martone
Aaron Martone
3,290 Points

An Object is simply a collection of key/value pairs. And yes, they both hold data. But a database is designed to do much more than hold data. It indexes it, provides optimizations to access, read, define in-depth meta about each field, restrict the values to data types (JS is a loose language, ie, it does not support strict data typing).

Simply put, an Object literal is a JS object, described in a literal method. What is a literal string? 'Hello, I am a literal String.'. What is a String Object? var myStringObject = new String('Hello, I am a String Object');. One was created via a 'literal' expression, the other via Object (because in JS, everything is an Object).

So I can create an object literal by using the following syntax:

var objectLiteral = {
    myKey1: 'A string value',
    myKey2: 23,
    myKey3: true
};

That is a object literal. If I want to create that same Object, I can do so with the Object.create() method as well as defining its individual key names and properties, like:

var pureObject = Object.create(Object.prototype);
pureObject.defineProperties({
    'myKey1': {
        value: 'A string value'
    },
    'myKey2': {
        value: 23
    },
    'myKey3': {
        value: true
    }
});

Literals are usually much less code to create.

A X
A X
12,842 Points

I much appreciate your examples, and that helps clear up the topic some for me.