Javascript

• Tags: [[What I Know]] [[Languages]] [[Web Development]]

• Syntax

  • Imports

    • CommonJS: const foo = require('foolib');
    • ES6: import foo from 'foolib';

  • Functions

    • There are a couple of main ways of defining functions:
    • Named declarations: function foo(bar) {}
    • Named expressions: const func = function foo(bar) {foo(bar.baz)}
    • Anonymous expressions: const func = function(bar) {}
    • Arrow: (args) => {} or arg => arg.something()}

  • Objects

    • Javascript is based around an Object model

    • Objects are essentially key value pairs, they can be accessed with dot syntax or bracket syntax

    • Can be created either with {} or new Object()

    • Examples:

         person.firstName = "Homer"
         person.lastName = "Simpson"
      
         var neighbor = {}
         neighbor['firstName'] = "Ned"
         neighbor['lastName'] = "Flanders"
         neighbor['catchPhrase'] = "Hi Diddly Ho Neighborino"
      

    • Complex objects containing nested objects and lists can be constructed using {} and [] constructs

             metadata: {
                 title: 'My Brain',
                 author: 'Aengus McMillin,
             },
             languages: [
                 'javascript',
                 'c#',
             ],
             published: true,
         }
      

• CommonJS vs ES6 Modules

  • It seems CommonJS is still used regularly in Node and the server side, whereas ES6 is becoming more standard for front end development
  • Gatsby doesn't seem to totally work with ES6 modules
  • VSCode recommends switching, this can only be disabled by adding a line to user/workspace settings
    • "javascript.validate.enable": false

• References

  • Mozilla Javascript Guide