Call() and Apply()

Call function and assign this.

Appear to be interchangeable?

Call uses list of parameters, apply uses array.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/call

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply

Const, let, var

Let - only used in the block it’s defined in?


const setYes = () => {

var varYes = 'yes'

let letYes = 'yes'

}


setYes()


console.log(typeof varYes) // undefined

console.log(typeof letYes) //undefined


if (1) {

 var varNo = 'no'

 let letNo = 'no'

}


// Only var varNo created within if statement available now.

console.log(typeof varNo) // string

console.log(typeof varYes) //undefined

https://medium.com/javascript-scene/javascript-es6-var-let-or-const-ba58b8dcde75

https://wesbos.com/let-vs-const/

https://wesbos.com/javascript-scoping/

Arrow functions

Explicit return without curly braces

https://wesbos.com/arrow-functions/

Map()

Calls function on items in array and returns result.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map