JavaScript ES6+ Notes

08 Jun, 2021

JavaScript ES6 Notes

Def vars const = cannot redeclare, cannot changed value let = can change value, cannot redeclare

let + const = if inside { } then it won't work outside

Concatination

• no need for + sign
• use backticks instead of quotes
• you can use single or double quotes inside backticks
• you can use variables inside of backticks like My name is ${name}

Object Literals If you want to return an object you don't need to do following

function getBook(name, author) {
  return {
    name: name,
    author: author
  }
}

If variable names are the same as the value you want to return, just use the variable instead like so

function getBook(name, author) {
  return {
    name,
    author
  }
}

**Object deconstruction*** Instead of list.item you can select multiple items

  name: "Shopping list",
  items: ['cow', 'milk'],
  car: xli
}

const {name, car} = list;

^ That will give me both the values

Arrow functions

• function keyword is not needed
• () are always required, unless you have one param only
• {} can be removed if you want to return just one line

const mylocation = (location) => {
  console.log(`My location is ${location}`)
}

defalut parameters You can set values like php in func params

New array functions

• forEach

    list = ['keyboard', 'mouse', 'laptop'];
    list.forEach((item) => {
        console.log(item);
    })
  

• map Map can copy a list and modify it to store into new array

  list = ['keyboard', 'mouse', 'laptop'];
  newlist = list.map(item => () {
    return item + 'new';
  })
  

• filter Get an array with only certain items from another array

  list = ['keyboard', 'mouse', 'laptop'];
  newlist = list.filter(item => () {
   return item == 'keyboard';
  })
  

#javascript