Learn Alpine, Lodash and Twit

Welcome to this beginner level series on Alpine JS! 👋🏞

Alpine JS is a rugged, minimal framework for composing JavaScript behaviour in your markup. It brings declarative, reactive, data-driven nature of libraries like React or Vue to your HTML templates.

In this series, you will learn about Alpine's handy **directives**. You'll discover how to define a component scope with `x-data`, run code on mount with `x-init`, attach event listeners with `x-on`, display data with `x-text`, decide wether or not to show an element with `x-show`, iterate through data with `x-for`, retrieve a DOM element with `x-ref`, learn how to achieve _two-way data binding_ with `x-model`, and much more.

You'll also learn how **"modifiers"** can be applied and chained to directives to provide additional functionality: control the animation transition of entering and leaving DOM elements, debounce an event listener, etc.

We'll also touch on what Alpine calls **"magic properties"**, which give you access to native browser events (`$event`), reference to DOM elements (`$refs`), and more.

You'll gradually discover Alpine's API and syntax, from building simple tabs to a mini app that fetches a dog picture based on a "breed" search field. 🐶

**Get ready to breathe some fresh air** - it's time to walk into cool, green Alpine pastures! 🏞

Alpine.js offers you the reactive and declarative nature of big frameworks like Vue or React at a much lower cost.

You get to keep your DOM, and sprinkle in behavior as you see fit.

alpine

Sprinkle declarative, reactive behaviour on your HTML with Alpine JS

In this course we’ll learn how to create Twitter bots. We’ll first learn how to interface with the Twitter API using Twit.js, which allows us to post statuses, search tweets, and interact with followers. We’ll create several example bots that show the diversity of possibilities, using powerful tools such as RiTa.js, Google’s Cloud Vision API, and Tracery. We’ll learn how to tweet data from Google Spreadsheets, and to compose and tweet a song for an audio bot. We’ll also learn how to host our bot logic on Heroku and Docker. 

Twitter API Client for node

Supports both the REST and Streaming API.

twit

Create your own twitter bots

[Lodash](https://lodash.com/docs/) is a collection of utilities that have become a staple of modern web development. This collection will show you how to re-create its most common methods using simple JavaScript techniques available in any modern web browser. In addition to re-building tools like `_.merge`, `_.get` and `_.debounce` from scratch you will also learn how to replace them completely in some cases with modern syntax such as [optional chaining](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining), [nullish coalescing](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing_operator) and [Object.fromEntries](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/fromEntries).

This collection should interest the following groups:
- Those who want to better understand common JavaScript patterns
- Engineers who want to reduce their dependence on Lodash (for performance or other reasons)
- Candidates preparing for a technical job interview (where it is common to be asked how to implement some of these methods).

JavaScript® (often shortened to JS) is a lightweight, interpreted, object-oriented language with first-class functions, most known as the scripting language for Web pages, but used in many non-browser environments as well such as node.js or Apache CouchDB. It is a prototype-based, multi-paradigm scripting language that is dynamic, and supports object-oriented, imperative, and functional programming styles.

javascript

Recreating Popular JavaScript Utility Methods from Lodash

In this lesson, we learn how the `x-init` directive in Alpine JS lets us run a JavaScript expression once the component has initiated.

We see the nuances that allow us to trigger that code before Alpine performs initial DOM updates, or after these updates have been made.

Focus in input field on page load with `x-init` in Alpine JS

In this lesson, we define a "count" state value with the `x-data` directive provided by Alpine JS. This defines a new scoped component, which can have access to this state.

We then display the "count" value in our HTML with the `x-text` directive, which updates an element's `innerText` value.

We also hook up buttons with click event listeners with `x-on:click`, which allows us to modify the count value as desired.

Update a count state value with the x-on event listener directive in Alpine JS

In this lesson, we create a set of tabs with Alpine JS, where only the content of the currently active tab is visible. To do this, we define an `activeTab` state value with `x-data. We then wire up our buttons to change the value of `activeTab` on click, and use `x-show` to determine if the tab content should be visible or not, based on the value of `activeTab`.

We also take control of the `class` attribute with `x-bind`, and we conditionally output an "active" class based on, you guessed it, the value of `activeTab`.

Toggle visibility and styles based on state with `x-show` and `x-bind` in Alpine JS

In this lesson, we move the component definition to a function, defined in a script tag in the HTML document.

We then iterate through an Array of Objects with the `x-for` directive in Alpine JS. We use a `<template>` tag to wrap the HTML element we want to repeat for each item, and put the `x-for` directive on that template tag.

We also define a "computed" property by adding a method on our function, which checks if a given ID matched the currently active tab id. This computed property allows us to determine wether or not to apply the "active" classname to our tab buttons.

Iterate through data with the `x-for` attribute in Alpine JS

In this lesson, we smoothen the transitions between tabs by applying a `transition` modifier to our `x-show` directive.

We see how we can ignore the leaving elements, and focus the animation on the entering elements. We tweak the transition duration and origin by chaining additional modifiers to our `x-show` directive.

Control enter and leave transitions with the `x-show.transition` modifier in Alpine JS

In this lesson, we see how the `x-model` directive makes achieving "two-way data binding" effortless in Alpine JS.

We see what it would take to recreate the same functionality with an `x-bind` directive for the input value, as well as an `@input` event listener which, thanks to an access to the browser's native events via the `$event` magic property, sets the state value to `$event.target.value`.

Keep a DOM input and state value in sync with the `x-model` directive in Alpine JS

In this lesson, we learn how to retrieve a DOM element via the `x-ref` directive in Alpine JS, which gives us a reference to the element it is applied on. In our case, an input field.

We can then use the `$refs` object, and reach for the ref we need to target.

This allows us to trigger the focus state of the input field, with the `.focus()` method.

Focus an input field on button click with `x-ref` and the `$refs` property in Alpine JS

In this lesson, we build a little app that fetches dog photos from the dog.ceo API, based on a "breed" search field. We want the API call to happen again when the search value changes, and to do so we use the `$watch` property from Alpine JS, which lets us define what state property we want to watch, and what callback function to run when a change happens.

We also use the `debounce` modifier on the `x-model` property to avoid firing an API call on each keystroke.

Refetch API data when a state value changes with the `$watch` property in Alpine JS

Welcome to this beginner level series on Alpine JS! 👋🏞

Alpine JS is a rugged, minimal framework for composing JavaScript behaviour in your markup. It brings declarative, reactive, data-driven nature of libraries like React or Vue to your HTML templates.

This is the series intro video. Let's get started!

Series Intro - Beginner Level Alpine JS

This lesson will demonstrate how to recreate a simplified version of the popular [lodash.merge](https://lodash.com/docs/4.17.15#merge) method from scratch.

First we'll create a test file with two objects that we want to merge together and demonstrate the output after running them through lodash.merge , then we'll go about creating our own version of the function.

Our initial version will support only one `source` object to merge in, and will support only the subset of JavaScript syntax supported by the JSON spec, including the following types:
- `boolean`, `number`, `string`
- object literal
- array

After getting basic types to merge we'll show off two methods for merging arrays, either using [concat](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/concat) or recursively going through the children and merging them.

Finally we'll build our own `isObject` function to check for object literals and recursively apply our `mergeJSON` function to any object literals in our `source` object.

And last we'll add support for multiple `source` objects to be merged in using a `for...of` loop.


**Note**

The `mergeJSON` method we create approximates the `lodash.merge` functionality but does not seek to replace it. It may be useful for some use cases, but primarily it's meant to be a tool for understanding how to merge objects with recursion.

Build lodash.merge from Scratch

This lesson will demonstrate how to replace common uses of [lodash.get](https://lodash.com/docs/4.17.15#get) with [optional chaining](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining) syntax.

`_.get` is by far my favorite lodash method. I've been on so many projects where the results of a network call was a large and often unreliable blob of data. After countless attempts to reign in errors caused by trying to access non-existent properties I've come to rely on _.get as a simple & safe way to retrieve data from those objects. However, as is always the case in web development, times are changing and the tools we need to safely access properties of complex objects are now being built into the platform. [Optional chaining syntax](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining) gives us the power of _.get without several of the tradeoffs. It doesn't require an extra library to use, it plays nicely with TypeScript and it can be used when calling methods as well as when accessing properties.

This lesson covers 4 common use cases of `lodash.get` and converts them to using optional chaining syntax.

1. Nested Object and Array Access
2. String and Variable Property Access
3. Calling a Method on an Object that may Not Exist
4. Providing a Default Value when a Property does Not Exist 

---

 ### Resources

- [Nullish coalescing operator](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing_operator)

Replace lodash.get with Optional Chaining Syntax

This lesson will demonstrate how to recreate a simplified version of the popular [lodash.get](https://lodash.com/docs/4.17.15#get) method from scratch.

Our function takes 3 parameters `obj`, `string` and `defaultValue`.

The primary technique we discuss is splitting the `string` on any kind of separator we might see such as `[`, `]`, or `.` and then filtering out any empty strings we get in our array. Once we have that array of path parts, we can loop through each part with a `for..of` loop then keep reaching into object until we either a) run out of parts to try 🎉 or b) hit a dead end (`null` or `undefined`). The entire function is very simple to write, but can be incredibly powerful when you're safely trying to access large and complex blobs of data that might be coming from a database or server response. 

Build lodash.get from Scratch

This lesson will demonstrate how to recreate a simplified version of the popular [lodash.debounce](https://lodash.com/docs/4.17.15#debounce) method from scratch. **I literally failed a job interview by messing up this question, so watch carefully!**

Debounce is an incredible tool most commonly used to prevent responding too quickly to user input that is in motion. For example, preventing excessive AJAX requests made while a user types into an autocomplete field or quickly responding to window resize events without bringing your browser to a halt.

Our approach is to build the simplest `debounce` method possible using a [setTimeout](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/setTimeout) which gets cleared each time the supplied function is called thereby delaying the execution of our function until input stops for a given amount of time.

The [Lodash implementation of debounce](https://lodash.com/docs/4.17.15#debounce) includes support for a number of options including `leading`, `maxWait`, and `trailing` which we have not covered in this video, but may in future lessons.

### Variations

Modern implementations of `setTimeout` include support for additional arguments which get passed into your function so an alternative to the approach used in this lesson would be `setTimeout(fn, wait, ...args)`

### ES5 Compatbility

If you are in an es5 environment skip the rest/spread syntax and use:

```
var args = Array.prototype.slice.call(arguments)
```

And later, in your setTimeout function:

```
fn.apply(null, args)
```

----

There are some really great resources out there to learn more about debounce, here are my two favorites:

- https://css-tricks.com/debouncing-throttling-explained-examples/
- http://benalman.com/projects/jquery-throttle-debounce-plugin/


Build lodash.debounce from Scratch

This lessons builds on [Build lodash.debounce from scratch](https://egghead.io/lessons/javascript-build-lodash-debounce-from-scratch) to add support for one of its more interesting options: `maxWait`. The `maxWait` option ensures that a debounced method is deferred no longer than the time specified. This is helpful if we need to respond to a long running interaction while it's still in progress. 

In this lesson we'll demonstrate how continuously typing into a debounced input field prevents us from logging any input at all. We'll add a `maxWait` option as a third parameter to our `debounce` function and set it up using an additional `setTimeout` call.

Essentially `maxWait` works by adding a second timer which will fire in the case that the normal debounce timer does not get called. We avoid unnecessarily triggering our debounced function by calling `clearTimeout` in both of our `setTimeout` functions to clear out whichever timer didn't just fire. We also need to set the `maxTimer` variable to `null` to tell our function it's safe to start a new maxWait timer each time either timer fires.


**Notes**

- `setTimeout` returns a timer ID not the actual timer object itself, which is why we have to `null` it out *after* we already call `clearTimeout`
- If you don't `null` out `maxTimer` in your original timer, the maxWait timer will stop triggering after the debounce timer is called the first time. I learned that one the hard way when I first recorded this video.


Extending debounce with a maxWait Option

`_.pick` and its sibling `_.omit` are popular utilities which apply filter-like functionality to objects. This lesson will demonstrate two different techniques for building the functionality found in [_.pick](https://lodash.com/docs/4.17.15#pick).

1. Using `for...of` to loop through the `keys` array
2. Using `for..in` to loop through the target object

This lesson will also cover how to emulate `_.pick`'s support for either an array or multiple arguments for the picked keys using [Rest params](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/rest_parameters) and [Array.prototype.flat()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/flat).


Build lodash.pick from Scratch

`_.omitBy` and its sibling `_.pickBy` are popular utilities which apply filter-like functionality to objects. Both of them accept a function to determine if a given entry in the object should be included in the output object. This lesson will demonstrate an approach to build both of these utilities from a single function using the combo of `Object.entries` and `Object.fromEntries`.

`Object.entries` converts an object into an array of key, value pairs. We couple that with the native Array filter method, to create a generate `filter()` method that works on objects. Once we've filtered our object we use `Object.fromEntries` to convert the array back into an object. This works great for both `omitBy` and `pickBy`.

**Note**

`Object.fromEntries` is part of the ES2019 spec and may need [a polyfill](https://github.com/ungap/from-entries) to work depending on your environment.

---

- [MDN Guide: Object.entries](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/entries)
- [MDN Guide: Object.fromEntries](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/fromEntries)



Build lodash.omitBy and lodash.pickBy with Object.fromEntries

We’ll get a real-time stream of tweets, and learn how to filter a stream by keyword, location, and user.

Use the Twitter Stream API with Twit.js

A modern JavaScript utility library delivering modularity, performance & extras.

lodash

This lesson shows how to refactor your old loops into using a simpler and more powerful lodash-style. We will start by looking at how many people traditionally write JavaScript `for` loops and then talk about the alternate style and benefits that Lodash offers.

Topics

Instructors

Content Type