Learn Angular-material, Lodash and Redwoodjs

[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

Angular Material is an Angular-native, UI component framework from Google. It is a reference implementation of Google's Material Design and provides >30 UI components and services essential for mobile and desktop AngularJS applications.

In this course, we will quickly build a real-work application Angular UI application, take a tour of Angular Material, and learn how ngMaterial can be used in your projects.

*presented by Thomas Burleson and Aaron Frost*

AngularJS is an open-source JavaScript framework, maintained by Google, that assists with running single-page applications. Its goal is to augment web-based applications with model–view–controller (MVC) capability, in an effort to make both development and testing easier.

angularjs

Introduction to AngularJS Material

RedwoodJS takes the JAMstack philosophy to the next level. It brings together all the tools modern web development has to offer:

- React
- GraphQL
- Prisma

RedwoodJS abstracts database management away from you so that you can just build your schema and it will do all the plumbing. This collection will go over how to create a RedwoodJS project and the scripts that will help make your developer experience a joy.


Bringing full-stack to the JAMstack

Do you love the JAMstack philosophy but need a database-backed web app? Want great developer experience and easy scaling? Redwood is here! Built on React, GraphQL, and Prisma, Redwood works with the components and development workflow you love, but with simple conventions and helpers to make your experience even better.

redwoodjs

Introduction to RedwoodJS: full-stack framework for JAMstack

React is one of the web’s most popular frameworks for building JavaScript applications. 

If you know what you’re doing, React can drastically simplify how you build, use, and maintain code.

Whether you’re a React newbie or you’re ready for advanced techniques, you can level-up with egghead. Explore our in-depth courses, lessons, and community resources to build more powerful applications and crack open your career.

react

We use `yarn redwood generate page` (`yarn rw` for short) in this lesson to generate an `IndexPage` component. 

The first argument to `yarn rw generate page` is the name of the page you are generating. The second argument is the path you want the page to show up on. So `yarn rw generate page index /` will generate an `IndexPage` component and insert a route entry in our `web/src/Routes.js` file.

We learn that redwood import `React` for you so you don't have to import it manually when you are creating a component.

Generate a Page Using the Redwood CLI

In this lesson, we are going over how to generate a `RedwoodJS` project.

We can create a `RedwoodJS` project with `yarn create redwood-app ./my-redwood-project`.

`yarn` will generate the `RedwoodJS` app in the file folder you specified without installing any globals.

To run the `RedwoodJS` app, we use `yarn redwood dev`. This runs the Redwood client as well as the `GraphQL` backend.

Generate a Redwood Project

RedwoodJS provides a `Link` component that we can use to navigate around our app. We can provide a `to` prop with the path that we want to navigate to.

RedwoodJS takes this a step further and provides a `routes` object from `@redwoodjs/router`. This object is aware of all the routes defined in `web/Routes.js`. This allows us to use the methods on this object rather than referencing the our routes with a string literal. We can then change the route path without having to change all of the references to that route all over our app.

Use RedwoodJS Link and routes Object to Navigate

RedwoodJS gives us a cli command to generate layouts.

`yarn redwood generate layout main`

This will generate a `MainLayout` component in `src/layouts/MainLayout/`. We can use this layout component to define any headers or footers we want to share across multiple pages. 

Extract a RedwoodJS Layout Component

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

The Angular Material Layout API wraps the flexbox CSS features with an amazingly easy, powerful HTML markup API. The Layout API hides the complexities of the CSS, is intuitive to use, and eliminates the need for developers to become flexbox experts to implement modern page layouts. 

In this lesson we will learn how to use the Angular Material Container components and the Layout API to implement the layouts specified in design wireframe.

> This course has been created by Thomas Burleson and Aaron Frost. 

Angular Material: Containers with the Layout API

Themes convey meaning through color, tones, and contrasts. And the theme color palettes, alphas, and shadows deliver a consistent tone to your application and a unified feel for all Angular Material UI components. Theming allows developers to change the intention and meaning of the application by changing the colors and shadows. 

Accessibility is a huge - often overlooked - feature in modern web applications. Angular Material components all implement ARIA features whenever possible. And for usage scenarios where the ARIA attributes are not explicitly provided and cannot be inferred, then Angular Material will provide details console warnings alerting the developer.

Let’s use the Angular Material Theming service to change the background, primary, accent, and warning colors used within the entire application. These will be configured at startup using the $mdThemeProvider.  

Let’s also resolve the two ARIA warnings shown in console. These originate from icon buttons where the ARIA label cannot be inferred. So let’s add a static aria-label and a dynamic, interpolated aria-label to those buttons.

> This course presented by Thomas Burleson and Aaron Frost

Angular Material: Theming and ARIA

Learn how to install Angular Material with `npm install`  and load the required libraries and stylesheets into your blank web page.

> This course has been created by Thomas Burleson and Aaron Frost

Angular Material: Installing with NPM

Angular is a development platform for creating applications using modern web standards. Angular includes a wealth of essential features such as mobile gestures, animations, filtering, routing, data binding, security, internationalization, and beautiful UI components. It's extremely modular, lightweight, and easy to learn.

angular

This lesson explores the Angular Material sidenav component. This includes input and display options, creating a sidenav with a nav list, and utilizing the `@angular/cdk` to update sidenav settings based on the users screen size.

Use the Angular Material Sidenav Component

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.

Lodash: Refactoring Simple For Loops

Most Angular Material UI components are declarative and used directly in the HTML markup. Some components, however, are programmatic and must be configured and invoked from Javascript. Programmatic components have a short-term, limited DOM lifespan and include Dialogs, Toast, and BottomSheet.

Let’s use the BottomSheet service to configure and display an Angular Material BottomSheet container which in turn will display a nested, custom Contact Sheet view.

> This course presented by by Thomas Burleson & Aaron Frost.

Angular Material: Using a BottomSheet

Both flexbox CSS and the Angular Material Layout allow web applications to `respond` to the size of the browser at any given point. No matter what the browser width may be, the web app adjusts its layout sizing accordingly. Combine responsive functionality with media query support and your web applications will have `adaptive` features to adapt to the width of the browser at a specific points. More than fluidly adjusting the widths and heights of elements, Adaptive applications can change the rendered UX with new positions, new components, and new styles. Angular Material Layout hides the complexities of implementing adaptive features with a singularly unique and simple HTML syntax.
Let’s use the Adaptive extensions of the Angular Material API to hide the SideNav on small devices (like iPhone or Android). We will explore the use of the $mdMedia service to easily lock open the SideNav on larger devices. And we will see how the $mdSideNav service can be used to programmatically close the SideNav after a user is selected.

> This course presented by Thomas Burleson and Aaron Frost.

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