Basic Example

01

Promise() Takes two functions as arguments, resolve(), and reject() 

function getWeather() {
    return new Promise(function(resolve,reject){
    })
}
let promise = getWheather()
console.log(promise)

We use promises when we need to wait for information or data

02

The data can be pased thru resolve() into a function using then() 

function getWeather(){
return new Promise(function(resolve,reject){
    resolve('Sunny')
})

}
const promise = getWeather()
promise.then(function(data){
    console.log(data)
})

03

The same would work for reject(), if we pass data into the second argument 

function getWeather() {
    reuturn new Promise(function(resolve,reject){
        // resolve('Sunny')
        reject('error' )
    })
}
const promise = getWeather()
promise.then(function(data){
        console.log(data)
    },function(rejectData){
        console.log(rejectData)
    }
)

04

A Promise works well with async code, or data not yet recieved, **Note you can call the function getWeather directly when it returns a promise, and we can pass other functions into then and the argument is automatically passed in 

    function getWeather() {
        return new Promise(function (resolve, reject) {
            console.log('...waiting')
            setTimeout(() => {
                resolve('Cloudy')
            }, 90)
        })
    }
    function weatherSymbols(weather) {
        if (weather == 'Cloudy') {
            console.log('☁️')
        }
    }
    getWeather().then(checkWeather)

05 Console

console.log('1')

Promise() Takes two functions as arguments, resolve(), and reject() 

function getWeather(){
return new Promise(function(resolve, reject ))
}