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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Promises Lecture</title>
</head>
<body>
<main>
<h1>Intro to JavaScript Promises</h1>
<h3>Articles relevant to the local weather conditions...</h3>
<div id="articles"></div>
</main>
<!-- see Slack for keys.js file -->
<script src="keys.js"></script>
<script
src="https://code.jquery.com/jquery-3.4.0.min.js"
integrity="sha256-BJeo0qm959uMBGb65z40ejJYGSgR7REI4+CW1fNKwOg="
crossorigin="anonymous"></script>
<script>
"use strict";
// ====================================================================================
// ==================================== PROMISES ======================================
// ====================================================================================
/*
A promise is a wrapper for asynchronous data/actions.
Promises make writing asynchronous JS code cleaner (avoiding "callback hell" nesting).
Working with jQuery AJAX requests is very similar to promises
(can even use promises in later version of jQuery!).
Promises have now become VERY common in both client and server side JS.
You will very likely handle promises far more often than having to create them.
*/
// ============ Basic Example of Promise Creation and Handling
// a promise is made to do something
let goodKid = false;
const getCake = new Promise((resolve, reject) => {
setTimeout(() => {
if (goodKid) {
resolve("CAAAAAAKE!!");
} else {
reject("NO CAAAAKE!!! :((((");
}
}, 2000);
});
// once the promise is resolved or rejected, take additional action
getCake.then((data) => {
console.log(data);
});
getCake.catch((error) => {
console.log(error);
console.log(error);
}).then(() => {
console.log("Additional then");
return Promise.reject();
}).catch(() => {
console.log("Final catch");
});
// ============ Using Promises with jQuery version 3+
// jQuery AJAX methods
// $.ajax('https://swapi.co/api/people/1')
// .done(function(data) {
// console.log(data);
// })
// .fail(function(jqXHR, message) {
// console.log(message);
// });
// Using promise methods (jQuery version 3.x.x and after)
// $.ajax('https://swapi.co/api/people/1')
// .then(function(data) {
// console.log(data);
// })
// .catch(function(jqXHR, message) {
// console.log(message);
// });
// ============ !! WAIT EXERCISE !!
// see curriculum
// ============ Promise.resolve() and Promise.reject()
// Promise.resolve('one').then((one) => {
// console.log(one);
// return 'two';
// }).then((two) => {
// console.log(two);
// return 'three';
// }).then((three) => {
// console.log(three);
// });
// ============ Fetch API
// jQuery AJAX request example
// $.ajax('https://swapi.co/api/people/1')
// .done(function(data) {
// console.log(data);
// })
// .fail(function(jqXHR, message) {
// console.log(message);
// });
// Fetch API GET example
// fetch('https://swapi.co/api/people/1')
// .then((response) => {
// return response.json();
// })
// .then((data) => {
// console.log(data);
// })
// .catch(console.log);
// Fetch API POST example
// fetch('https://hookb.in/eKZ0mV6k1aTr9g86Q7JM', {
// method: 'POST',
// headers: {
// 'Content-Type': 'application/json'
// },
// body: JSON.stringify({
// username: "bill",
// password: "pass123"
// })
// })
// .then(console.log)
// .catch(console.log);
// ============ NY Times Articles Based on Forecast of Current Location
// function getForecast(coord) {
// return fetch(`https://cors-anywhere.herokuapp.com/https://api.darksky.net/forecast/${darkSkyAPI}/${coord.lat},${coord.lng}`)
// .then(res => res.json())
// }
//
//
// function getCurrentLocation() {
// return new Promise(function(res, rej) {
// navigator.geolocation.getCurrentPosition(function(pos) {
// res({"lat": pos.coords.latitude, "lng": pos.coords.longitude});
// });
// });
// }
//
// function getLocalForecast() {
// return getCurrentLocation()
// .then(getForecast)
// }
//
// function getNYTimesArticle(search) {
// const apiKey = apiKeyNYT;
// return fetch(`https://api.nytimes.com/svc/search/v2/articlesearch.json?q=${search}&api-key=${apiKey}`)
// .then(res => res.json());
// }
//
// function buildWeatherHtml(articles) {
// return articles.reduce((accum, curr) => {
// return accum += `
// <article>
// <a href="${curr.web_url}">${curr.headline.main}</a>
// </article>
// `
// }, "");
// }
//
// getLocalForecast()
// .then(forecast => {
// console.log(forecast.currently.summary);
// return forecast.currently.summary
// })
// .then(getNYTimesArticle)
// .then(data => {
// document.getElementById("articles").innerHTML = buildWeatherHtml(data.response.docs);
// });
// ============ Promise.all()
// const getCoffee = (type) => {
// return processOrder(type);
// };
//
// const processOrder = (type) => {
//
// let orderAndPay = new Promise((resolve, reject) => {
// setTimeout(function() {
// resolve(`Coffee of type ${type} has been ordered and paid for!`);
// }, 2000);
// });
//
// let makeOrder = new Promise((resolve, reject) => {
// setTimeout(function() {
// resolve(`Coffee of type ${type} is ready!`);
// }, 4000);
// });
//
// return Promise.all([orderAndPay, makeOrder]);
//
// };
//
// getCoffee("espresso").then((data) => {
// console.log(data[0]);
// console.log(data[1]);
// console.log("You now have a coffee!");
// }).catch((err) => {
// console.log(err)
// });
// ============ Promise.race()
// const color1Promise = new Promise((res) => {
// setTimeout(res, 2000, fetch('./data/color.json'));
// });
//
// const color2Promise = new Promise((res) => {
// setTimeout(res, 1000, fetch('./data/color2.json'));
// });
//
// const getColor = () => Promise.race([color1Promise, color2Promise]);
//
// getColor().then(response => response.json()).then(data => console.log(data));
//
// ====================================== ADDITIONAL EXAMPLES
// ===================== Using Asynchronous Actions and Stacking .then()
// let good = false;
//
// const bakeCakeIfGood = new Promise((resolve, reject) => {
// if (good) {
// resolve("I'll bake you a cake! :)");
// } else {
// reject("Error");
// }
// });
//
// // bakeCake returns a promise when called
// const bakeCake = new Promise((resolve, reject) => {
// setTimeout(() => {
// resolve("Your cake is baked. Enjoy!");
// }, 3000);
// });
//
// bakeCakeIfGood.then((result) => {
// console.log(result);
// return bakeCake; // here I am getting another promise that I can call .then on
// }).then((result) => {
// console.log(result);
// }).catch((err) => {
// console.log(err);
// });
// ============ Promise Chaining
// function countSlow(count) {
// return new Promise(function(res) {
// setTimeout(function() {
// console.log(count);
// res(++count);
// }, 500);
// });
// }
//
// countSlow(1)
// .then(countSlow)
// .then(countSlow)
// .then(countSlow)
// .then(countSlow);
// ===================== Chaining asynchronous actions
// won't work :*(
// const goGetPizza = () => {
// setTimeout(() => {
// console.log("I've got the pizza!");
// }, 2000);
// };
//
// const cookPizza = () => {
// setTimeout(() => {
// console.log("Pizza is cooked!");
// }, 2000);
// };
//
// const eatPizza = () => {
// setTimeout(() => {
// console.log("Pizza is eaten!");
// }, 2000);
// };
//
// goGetPizza();
// cookPizza();
// eatPizza();
// ugly solution...
// const goGetPizza = () => {
// console.log("I've got the pizza!");
// };
//
// const cookPizza = () => {
// console.log("Pizza is cooked!");
// };
//
// const eatPizza = () => {
// console.log("Pizza is eaten!");
// };
//
// const doPizza = () => {
// setTimeout(() => {
// goGetPizza();
// setTimeout(() => {
// cookPizza();
// setTimeout(() => {
// eatPizza();
// }, 2000);
// }, 2000);
// }, 2000);
// };
//
// doPizza();
// better promises solution
// const goGetPizza = () => {
// return new Promise((resolve, reject) => {
// setTimeout(() => {
// resolve("I've got the pizza!");
// }, 2000);
// });
// };
//
// const cookPizza = () => {
// return new Promise((res) => {
// setTimeout(() => {
// res("Pizza is cooked!");
// }, 2000);
// });
// };
//
// const eatPizza = () => {
// return new Promise((res) => {
// setTimeout(() => {
// res("Pizza is eaten!");
// }, 2000);
// });
// };
//
// const doPizza = () => {
// goGetPizza().then(m => {
// console.log(m);
// return cookPizza();
// }).then(m => {
// console.log(m);
// return eatPizza();
// }).then(m => {
// console.log(m);
// }).then(() => console.log('Extra .then() runs'))
// .then(() => 3)
// .then(three => three)
// .then((num) => console.log(num))
// .then(() => console.log('Will this run???'))
// .catch(e => console.log(e));
// };
//
// doPizza();
// ======================= WAIT EXERCISE
// const wait = num => {
// return new Promise((res) => {
// setTimeout(res, num);
// });
// };
//
// wait(1000).then(() => console.log('You\'ll see this after 1 second'));
// wait(3000).then(() => console.log('You\'ll see this after 3 seconds'));
</script>
</body>
</html>