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roadmap roadmapFrontEnd

I'd recommend just searching for things you need here Big tip: on a mac you can use control + cmd + space to insert emojis ⛹🏽⛹⛹

Where I'm at now: Frontend: Web components Backend: OS

Backend:

Internet

Basic Front End

OS and General Knowledge < DO THIS!

  • OStep, skim this: https://drive.google.com/file/d/1iPD0JzZ5OSvIS03e_PkymYf4ySEeGjQX/view?usp=sharing (you are on chapter 11)

    • How do OSes work? Virtualization, Concurrency and Persistence ✔️

    • Process Management

      • Process API: Create, Destroy, Stop, Start, Wait, Status.
      • Create: Modern OSes lazy load the important bits of an EXECUTABLE program from an SSD into memory
      • Memory Allocation in the form of a heap(user allocated, ex: malloc) and a stack(stores argc and argv array on initialization).
        • requires Paging and Swapping.
      • Each process has 3 file descriptors STDERR, STDIN, STDOUT
      • Process states:
        • running
        • blocked
        • ready process states
      • Some OS APIs
        • fork() - creates a parallel process of the program which it was called from
        • wait() - let's the parent wait for the child process to finish(also provides determinism)
        • exec() - runs a different program using the same process

    • Threads and Concurrency

    • Memory Management

      • Heap
        • malloc() stores in heap, free() releases it
        • How can i not call free() when I run a short-lived program?
          • Well, the OS gives you two abstract layers of the memory, some for the process AND some within each process. So for shorter-lived programs not calling free is okay because the OS frees the process and the heap was created in the second level of abstraction, the per process memory.
      • Segmentation
        • Storing Code, Stack and Heap in ways that allow minimal space wastage
        • Paging
          • Storing data in pages
        • Swap space
          • Location of virtual memory save to swap pages
      • Page fault
        • When a page is not available in virtual memeory it looks send a page fault or a page not available and fetches the page from the physical memory
      • Pages are replaces as required using a page replacement policy
      • Workloads of policies and their performance
        • No locality
        • 80-20 workload
        • looping workload
      • TLB
        • provides the system with a small hardware cache of address translations
      • Address translations
        • Converts memory addresses to physical addresses

    • Interprocess Communication

    • I/O Management

    • POSIX?

    • Terminal commands:

      • grep
      • awk
      • sed
      • lsof
      • curl
      • wget
      • tail
      • head
      • less
      • find
      • ssh
      • kill

Learn a language

  • Okay i just got the shaft in an interview for not knowing js well enought. Qs?: What are promises, Event loop, What really is node.js.
  • I'll post links from the bookmarks.

Relational databases

MySQL: https://www.udemy.com/course/mysql-and-sql-from-beginner-to-advanced/learn/lecture/5050050#overview

  • The freecodecamp course is good for postgres.
  • Need to answer questions like what are relational databases and why use them.(ACID)
  • Did you know mongo was eventually consistent

FrontEnd

Internet ✔️

HTML

Semantic HTML

CSS

Responsive design and media queries: https://www.youtube.com/watch?v=fgOO9YUFlGI&list=PLoYCgNOIyGABDU532eesybur5HPBVfC1G&index=9&loop=0 review FEM 1:

  • Responsive Design:
    • Flexible Grid Based Layout
    • Media-Queries
    • Images that resize
  • Floats
    • Hack for layout
    • "The float property is used for positioning and formatting content e.g. let an image float left to the text in a container."
  • box-sizing: border-box (uses the border box model that includes the width of the content, border and margin all in to the box.
    • make everything inherit it: *, *:before, *:after { box-sizing: inherit; }
  • col-md-4?
    • bootstrap syntax
    • md: width of page is >= 768 px
    • 4: spans 4 of the twelve columns in the page

JS

Fetch api

  • Axios

Version Control ✔️

Web security

  • Not done much besides owasp, cors and https, do more of the latter two(check out the guide from the backend section)

CSS Architecture

CSS Preprocessor

Build Tools

Task Runners

Npm scripts ✔️

Module bundlers

Parcel baby!

Linters and formatters

  • Prettier plugin
  • eslint files or jetbrains plugin

Pick a Framework :

React

FEM React https://btholt.github.io/complete-intro-to-react-v5/

  • useEffect hook , need to declare dependencies or it will 'useEffect' every time render is called.
  • dropdowns are great for custom hooks
  • useEffect replaces the lifecycle methods
  • general js, but if you get a map back that looks like : destructure

you can get just the names from it by using destructuring: const breedStrings = breeds.map(({name}) => name)

Vue

Nuxt: essentially Next for Vue, Gives you SSR and code-splitting(basically treeshaking for your library)

How to learn: Just go through the Vue docs.

Vshow v vIf: Vif mounts and unmounts components which can be expensive, so it's good for large components with less toggles. V show on the other hand is for lots of toggles/ smaller components.

Slots are essentially like props except you can pass in tags too

using props with the : (short for v-bind) will let you pass in state and without will just pass in the literal in the component tag

State management

  • need to do the FEM Redux course
  • Context ✔️

Modern CSS

  • find a class on emotion, FEM has one

Composition API

  • Essentially react's hooks

Interview Questions:

JS

  • 10 points i should check out sometime: https://medium.com/javascript-scene/10-interview-questions-every-javascript-developer-should-know-6fa6bdf5ad95

  • Essential JS interview questions https://medium.com/javascript-scene/master-the-javascript-interview-what-s-the-difference-between-class-prototypal-inheritance-e4cd0a7562e9

  • What is a javascript? A single-threaded non-blocking I/O, Concurrent language. (concurrent meaning able to run multiple process at the same time as opposed to parallel that allows the starting of two proceesses at the same time. k, so what's the IO part, just the requests being the output and their responses being the input. Single threaded? we can dive into the event loop and how all of that is handled.

  • What is lazy evaluation? Calling a function using FP's first order functions and closure's we can create a lazily evaluated function that runs only as required. This is useful for functions that are super heavy and so just running them at the time they are needed is a good idea rather than starting them early. https://www.codementor.io/@agustinchiappeberrini/lazy-evaluation-and-javascript-a5m7g8gs3. If you run the function twice do you need to actually run it twice. No cause memoization.

  • What is the event loop? Part of the engine but control over it is give to the runtime as well.

  • What's the difference between the JS runtime and engine? A JS program must do two things:

    • parse your code and convert it to runnable commands
    • provide some objects to javascript so that it can interact with the outside world. The first part is called Engine and the second is Runtime.

    For example, the Chrome Browser and node.js use the same Engine - V8, but their Runtimes are different: in Chrome you have the window, DOM objects etc, while node gives you require, Buffers and processes.

  • What is asynchronous programming? Synchronous programming is a program that blocks for long processes like disk IO and network requests. Au contraire, A-synchronous programs do not wait, they pass the, otherwise blocking, sections of the code on to the callstack where they are let to run to completion if they can using the engine, and if not they are passed to web APIs provided by the Runtime(think DOM in the front end and Require in the backend). On completion they can't just go straight back to the call stack so they are moved to a message queue called a task/callback queue. This then pushes the completed callback over to the call stack where it finally get's to run. EventLoop

  • Can you name two JS paradigms? Javascript allows you to program procedurally(think like C) with OOP if you chose to. Also functionally. The OOP is supported by prototypal inheritance. Prototypical OOP in JS: https://medium.com/javascript-scene/the-two-pillars-of-javascript-ee6f3281e7f3 Functional programming in JS: https://medium.com/javascript-scene/the-two-pillars-of-javascript-pt-2-functional-programming-a63aa53a41a4

  • Class inheritance vs prototypical inheritance? https://medium.com/javascript-scene/master-the-javascript-interview-what-s-the-difference-between-class-prototypal-inheritance-e4cd0a7562e9

    You essentially get an object and thus can just the parts of the object that you need and not have access to everything else. With Class inheritance you always get the entire class delegation hierarchy. This means sometimes you might want just the banana but might get the gorilla holding it and the whole jungle with it too.

  • What are two-way data binding and one-way data flow, and how are they different?

  • two-way data binding is essentially the ui mapping the model data, in react, the state and vice versa.

  • one way data flow references the fact that the model is the single source of truth and all changes in the ui head towards it.

  • What does “favor object composition over class inheritance” mean? You essentially avoid all the weaknesses of OOP

    • The weak base class problem
    • Avoid creating a class hierarchy

  • What tings do you get with a functional programming language? first-class functions, Closures, Higher-order functions

  • What is a promise? Todo: https://medium.com/javascript-scene/master-the-javascript-interview-what-is-a-promise-27fc71e77261

  • Wtf is a Closure?

    • So in js, functions form closures. So when you create a function, it stores the entire lexical scope along with the function itself. This is pretty rad cause you can do this: function init() { const name='Mozilla'; function displayName() { console.log(name); } return displayName; }

    const functionVal = init(); functionVal(); // this will actually printout 'Mozilla' :O

    • K, so it can also be used to create a function factory: function makeBirthday(name) { //wow this is sad return function() { console.log("Happy Birthday" + name)
      }

      makeBirthday("Vignesh")

      but what's way cooler is using it to create private methods var counter = (function () { var privateCounter = 0; function changeBy(val) { privateCounter += val }

      return{ increment: function() { changeBy(1) }, decrement: function() { changeBy(-1) }, value: function { return privateCounter; } }

      })();

      console.log(counter.value()); // 0

      counter.increment(); console.log(count.value()); // 1

    You can use closure scope chains like: var e = 10; function sum(a){ return function(b){ return function(c){ // outer functions scope return function(d){ // local scope return a + b + c + d + e; } } } }

    to require values to be put in in order and not return anything unless they are there.

  • What is a higher-order function? todo: https://eloquentjavascript.net/05_higher_order.html Essentially a function that takes in two functions as parameters and returns a combined function

  • move to correct location: TCP /(over) IP: https://www.cloudflare.com/en-in/learning/ddos/glossary/tcp-ip/

  • What is a promise?

    • A promise is a returned object that you attach a callback to to get the response of an asynchronous operation. It's different from a callback because it gives you guarantees of responding with either success or failure.
    • Did you know the thing( the function lol ) that you pass into setTimeout is a callback, and shitty old APIs might not already return promises. If you instead wrap the two weird things in a promise like const wait = new Promise(setTimeout(doSomething, 1000)). You can just run wait and should probably only do that to deal with the code.
    • K so that syntax was off, it's actually like this const wait = ms => new Promise(resolve => setTimeout(resolve, ms));
    • Always return results, ms => new Pro... is short for function (ms) { returns new Pro... }
    • So what is a promise? It's a callback that is used to wrap another callback. I honeeestly don't know okkekekke. Let me read callbacks and see if I get it. if not the medium. So a promise is an object wrapper for a callback. It gives you guarantees of completion and can be chained.

  • What is a callback?

    • A function that is passed into a function and then called by the function that did the passing in(the outer function). A shitty but i guess kind of clear example of how annoying callbacks are:

function greeting(name) { alert('Hello ' + name); }

function processUserInput(callback) { var name = prompt('Please enter your name.'); callback(name); }

processUserInput(greeting);

  • K so how is this tied into what a promise is. So a promise wraps all of this in a callback and is an object that represent it. so by doing so you can just call the parent Obect and say .then and it will essentially guarantee the nastiness that is callbacks is done(success or not). Ew. But i see why promises are so loved. Because they give you an object interface that can be passed around a lot easier than callbacks.

  • What is lazy eval? https://www.codementor.io/@agustinchiappeberrini/lazy-evaluation-and-javascript-a5m7g8gs3

  • What is prototypal inheritance? Inheritance using the built in prototype object in JS rather than classes because of thing like the weak base class problema and the banana problem(the whole gorilla)

  • Where do you store a JWT on the front end? in http-only cookies so that they are safe from XSS. They can be set by the server by sending a Set-Cookie header. A 'Secure' and 'Http' flag can also be made necessary so that they prevent Man in the middle attacks and XSS respectively.

https://stormpath.com/blog/where-to-store-your-jwts-cookies-vs-html5-web-storage https://developer.mozilla.org/en-US/docs/Web/HTTP/Cookies

  • What did you learn from the two pillars?

    • FP and it's uses, higher order functions being used to take two functions together and combine them, closure used to encapsulate and create contract factories, Lazy loading that is enabled by closures and first class functions together allows you to run an expensive function only when it is needed and cache it for later usage. First order functions which enable functions to be passed into other functions as objects.
    • Prototypical inheritance

  • How does TLS work? https://medium.com/iocscan/transport-layer-security-tls-ssl-8e02b6d1d648 Client says hello(and it's available encryption ciphers), server responds with it's certificate(and chooses the most secure cypher available), client verifies the certificate with certificate validating authority. Client and server agree on keys and exchange keys. Http request is encrypted with symmetric key. response is encrypted with symmetric keys.

  • How does Http work? Over tls in a client-server fashion.

  • Cookies vs Local storage? Cookies are essentially used only by the server side and local storage is only used by the front end.

  • What is a first-class function? Apparently when you can pass a function into another function it's then called a first class function. Essentially they inherit from JS's Object and thus can be passed around like one.

  • How is lambda calculus related to functional programming? Does it have anything to do with lambda calculus? ( Church as opposed to Turing baybee). Functional programming is heavily based on lambda calculus. Func. prog. uses pure functions and thus avoid side-effects. A lambda function isn't really related, it's just a function with no name.

  • What is a pure-function? They are all about mapping inputs to outputs. Get that? A fixed input always returns a fixed output. So there's no shared state and thus they can be used to avoid tons of bugs. some examples are map, reverse, find, maybe a custom forloop fp.

  • Pure functions don't cause any side effects? what's a Side effects? Side effects just mean that running the function will not affect the state outside the function.

  • Okay I really really want to do anything in my power to understand functional programming, how do? https://softwareengineering.stackexchange.com/questions/130722/what-is-the-difference-between-a-function-and-a-lambda

Turing-Church and their relation and their work turing into the two paradigms of computing we have today still get's me hard excited to this day.

Fem

https://frontendmasters.com/books/front-end-handbook/2018/practice/interview-q.html

Bonus(Common to both)

Other niceties: