Wes Bos JS notes

VS code change es-lint settings 

https://bit.ly/3g6Lwde
CTRL + SHIFT + P, type workspace settings (JSON) and press ENTER. 


Slice vs Splice
const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9];

slice // immutable ( does not mutate original array ) 
const sliceArr = numbers.slice(1, 5);
console.log(numbers); // [1, 2, 3, 4, 5, 6, 7, 8, 9];
console.log(sliceArr); // [2, 3, 4, 5];

splice // mutable ( does mutate original array )
const spliceArr = numbers.splice(1, 5);
console.log(numbers); // [1, 7, 8, 9];
console.log(spliceArr); // [2, 3, 4, 5, 6];


add item to middle of array

const addWord = [...numbers.slice(0, 3), "STUFF", ...numbers.slice(3)];
console.log(addWord); // [1, 2, 3, "STUFF", 4, 5, 6, 7, 8, 9]

remove item in middle of array
const removeNumber5 = [...numbers.slice(0, 4), ...numbers.slice(5)];
console.log(removeNumber5); // [1, 2, 3, 4, 6, 7, 8, 9]


More Array methods and related Object methods to review

Array.from() Array.isArray() 

.join() .pop() .push() .shift() .unshift() [...spread] .flatten() 
.slice() .splice() .indexOf() .reverse() .includes() .find() 
.filter() .some() .every() .sort() 

Object.entries() Object.keys() Object.values() Object.fromEntries()