Created
November 5, 2020 04:24
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introducing Promises
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const orderCheeseburger = (goodFortune) => { | |
return new Promise((resolve, reject) => { | |
if(goodFortune) { | |
resolve('your cheeseburger! :)') | |
} else { | |
reject('out of cheeseburgers. :(') | |
} | |
}) | |
} | |
const outcome = orderCheeseburger(true) | |
.then(result => { | |
return result | |
}) | |
.catch(err => console.log('Reject state:', err)) | |
// calculator example | |
const calculate = (a,b) => { | |
return new Promise((resolve, reject) => { | |
if(typeof(a) !== "number" || typeof(b) !== "number") { | |
reject('must provide number for arg') | |
} else { | |
resolve(a + b) | |
} | |
}) | |
} | |
const result = calculate(1,2) | |
.then(res => { | |
console.log(res) | |
return res | |
}) | |
.catch(err => console.log(err)) | |
console.log(result) | |
// write greeting function | |
// takes 1 arg, name | |
// if there is no name provided reject | |
// if there is a name resolve with the greeting and name combined | |
function greet(name) { | |
return new Promise((resolve, reject) =>{ | |
if(name){ | |
resolve('hello ' + name) | |
} else { | |
reject('please provide a name') | |
} | |
}) | |
} | |
const salutation = greet('Alejandro') | |
.then(res => console.log(res)) | |
.catch(err => console.log(err)) | |
console.log(salutation) |
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