Thursday, March 17, 2022

Web Development Basics 2022

  • ES6 JavaScript - ECMA pronounced ehk-ma decides the standard for javascript. And that's why the newest version of JavaScript is called ES6, ecmascript 6. symbol is new in ES6.
  • JavaScript - Dynamic Typing - Don't have to declare types right away.
  • JavaScript - Primitive Types (no methods, immutable): undefined, null, boolean, number, string, symbol. 
  • Toast message : a temporary message, for example display error.
  • array can store data with different types.
  •  HTTP status code 
    • introduction:
    • Different versions of it
    • MDN
    • Typecasting: changing a variable from one time to another. 
    • Coercion: explicit versus implicit. We need to watch out for this in JavaScript. Often it doesn't work as we would expect. 
    • Comparison and testing. Double equal versus triple equal. Double equal will coerce the types then test. Triple equal will require the type to match as well. This too can be counter intuitive, unexpected in JavaScript. There are also quirky JavaScript equality issues. JavaScript quirky equality issues
  • HTML DOM : Web dev Document Object Model (DOM) turns html documents into a tree like structure of nodes. nodes include img, body and the element node can contain attribute nodes such as src, text. A common task is traversing DOM elements.

Use ready to use, low-code environment:
Did you know you can upload custom font to Wix? Wix let's you start websites using a bit of HTML and CSS. 

Debugging : 

Node.js out of memory error. If encountered try upgrading node js to the latest version see if the problem is resolved. 

JavaScript events
JavaScript addEventListener, js events

Web Server request and response
Can return, de-couple tuple request object result into header, url and method
package.json the file that describes the node project, also specify dependencies, 
npx comes bundled with node
Key concept : request response cycle between client and server
Header is made of key value pairs, such as token value
Body response or data sent to server form date
node js http module is useful handle web requests.

JavaScript allows trailing comma. The extra last comma in objects. And that is okay. 

Content delivery network (CDN)

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Error Message Hardhat debugging error unsupported engine hardhat, current node v18

Error message npm WARN EBADENGINE  Unsupported engine { package: 'hardhat@2.9.3', required: { node: '^12.0.0 || 14.0.0 || 16.0.0...