# ES6 Recap

## ![](https://ga-dash.s3.amazonaws.com/production/assets/logo-9f88ae6c9c3871690e33280fcf557f33.png) ES6 Recap

## ES6 Recap

We've just learned a bunch of ES6.

We've learned:

#### Use `const` and `let` instead of `var`

Remember, When declaring variables using ES6 syntax, if you need to declare a variable whose value will *not* change, declare it as a `const`. If the variable's value *will* or *might* change, unless you need a global scope, you'll likely declare it as a `let`.

#### Use the arrow function `=>` to declare a function

```javascript
const addTwo = num => {
 return num + 2;
}
```

#### Use the arrow function `=>` with implicit returns to declare a function that only returns something

```javascript
const addTwo = num => num + 2;
```

#### Use the arrow function `=>` preserves the original `this` context

```javascript
function eatBreakfast(pancakes) {
  var that = this;
  that.food = 'Knife please?';
  Waiter.bringCutlery(function (silverware) {
    that.food = silverware;
  });
}
```

is now

```javascript
const eatBreakfast = pancakes => {
  this.food = 'Knife please?';
  Waiter.bringCutlery((silverware) => this.food = silverware);
}
```

#### Use literals for assigning a variable as the value of the key of the same name

The second piece of code is synonymous with the first piece of code. The second piece of code saves you from writing `price: price` when you're declaring an object key-value pair inside an object.

```javascript
 const price = 100;
 const item = {price: price};
```

```javascript
 const price = 100;
 const item = {price};
```

### Use template literals for string interpolation

Remember, these require you to use the `tick` \`\`\` quotation mark. The single quote or double-quote marks won't invoke string interpolation.

```javascript
 const greeting = name => `Hi, ${name}.`;
```