# Left Hand Side

In JavaScript, you may hear the expressions "left side" or "right side" when talking about declarations. These refer to evaluations or comparisons, and to which side the particular expression is on. (eg `let x /*left side*/ = 12 /*right side*/`) Here we will focus on the left hand side, and specifically the keywords `new` and `super`.

## new

`new` is a keyword that lets a user create an object based off of a user-designed model. The model must be created first as a function, like this:

```javascript
function Game(score, winner, loser) {
    this.score = score;
    this.winner = winner;
    this.loser = loser;
}
```

`this.score` refers to the property of the object being created, while `score` refers to the parameter being passed into the function. We can create a new Game object with the following:

```javascript
let SBLII = new Game(41-33, "Philadelphia Eagles", "New England Patriots");

console.log(SBLII.loser); //"New England Patriots"
```

## super

Sometimes the information inside of an object is so large that we store it inside another object within the first. This is called "nesting". Think of it like a news program:

```javascript
let news = {
    story 1: "headline",
    story 2: "important",
    weather: {
        tomorrow: "sunny",
        wednesday: "rain"
    },
    sports: {
        baseball: "Home run!"
        football: "Touchdown!",
        ...
    },
    function throwToCommercial(segment, time) {
        console.log("We'll be back with " + segment + " in " + time + "minutes after this short break.");
    }
    ...
}
```

`news` is the parent object, whereas `sports` and `weather` are the child objects. Unfortunately for our news program, the commercial break function lies in the parent object, meaning that the children can't go to commercial. We use the `super` keyword in these situations to allow the child objects to access properties of the parent. The newscasters can just call the method themselves (`this.throwToCommercial('weather', 3)`), but if the weatherman tried to use `this`, he'd get an error. The weatherman has to go to break like this:

```javascript
super.throwToCommercial('sports', 2);
```

## File Location

We will be working in the following file:

```
    javascript-library
        └── 0-PreWork
        └── 1-Fundamentals
            └── 1-Grammar-and-Types
            └── 2-ControlFlow-and-ErrorHandling
            └── 3-Loops
            └── 4-Functions
            └── 5-Expressions-and-Operators
                01-assignment.js 
                02-comparision.js 
                03-ternary.js
                04-typeof.js 
                05-this.js 
                06-left-hand-side.js <----You will be working in this file.
```

## Practice

1. Create a function to be used as a model for today's date, then use that model to create an object called today.
2. Add a property to the today object called tomorrow (`let today.tomorrow = ...`).
3. Using the news example from above, add the propery `localNews` to the object, then have the sportscaster go to commercial, teasing the local news coming up in 3 minutes.


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