JavaScript Fundamentals

JavaScript Fundamentals

1. Variables

   • Primitives
     • Number
     • Strings
     • Booleans
   • var
     • Descontinued
   • let
     • Take the value just inside the scope
   • const
     • Cannot change the data inside it
     • Must have a value on initialize
   • null
     • It's an object
       • Can cause bug

2. NodeJS

   • Runs javascript code in backend
   • Libs
     • Errors lib
       • https://nodejs.org/api/errors.html#errors_errors
     • console lib
       • https://nodejs.org/api/console.html

3. Operators

   • Converter
     • Explicite
       • string2number
         • Number(string)
       • number2string
         • String(number)
     • Implicite
       • ==
         • Can cause bug
   • Comparison
     • ===
       • Compare variables values and types
         • BEST PRACTICE
     • ==
       • Compare just variables values
   • Lib Operators
     • https://developer.mozilla.org/pt-BR/docs/Web/JavaScript/Guide/Expressions_and_operators
   • Ternary
     • variable1 >= variable2? "Case True" : "Case False"
   • Template String
     • string = `A string goes here ${variable1}, and ${variable2} here.`;
       • Can be used together ex: `${age >= 18 ? yes : no}`
   • Repetition
     • for
       • for(variable; condition; variable++{ block of code }

4. Functions

   • function nameOfFunction(parameters){ block of function}
   • Libs
     • math
       • https://developer.mozilla.org/pt-BR/docs/Web/JavaScript/Reference/Global_Objects/Math#description
   • Functions / Expressions
     • variable = function(parameters) {return output}
   • Arrow Function
     • Behavior like expression
     • let variable = (parameter1,parameter2,parameterN) => return output
   • Callback
     • https://developer.mozilla.org/pt-BR/docs/Glossary/Callback_function
     • array.forEach(element,index)
       • Not returnable values
     • array.map
       • Returns an array with values

5. Features

   • dynamic typing
     • Untyped
       • multiple paradigms
         • Hoisting functions and variables

6. Data Structure

   • Array
     • Methods
       • https://developer.mozilla.org/pt-BR/docs/Web/JavaScript/Reference/Global_Objects/Array
       • array.pop
         • - element on last index
       • array.push
         • + element on last index
       • array.slice
         • Split an array
       • array.splice
         • - elements on specific indexes and + element
       • array.concat
         • concatenate two arrays
       • array.includes
         • Returns true or false
       • array.indexOf
         • Returns the index of the element inside array
       • sort
         • https://developer.mozilla.org/pt-BR/docs/Web/JavaScript/Reference/Global_Objects/Array/sort

7. Objects

   • key-value
     • objectName.key
     • objectName = {key1: value, key2: value, keyN: value}
     • delete
       • delete objectName.key
     • Arrays can be used as values
   • Manipulation
     • https://developer.mozilla.org/pt-BR/docs/Web/JavaScript/Reference/Global_Objects/Object/create
     • Spread Object
       • https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax
     • Prototype
       • function objName (keys){this.key = key}
         • let newobject = new objName()
     • inheritance
     • Destructuring
       • [...arrayName1,...arrayName2]
   • Classes
     • Attributes
       • Characteristics
     • Methods
       • Behaviors
     • Inheritance
       • Extends
   • Is a class instance