JavaScript: Past, Present, and Future - NDC Porto 2020

Ah, JavaScript! Like it or not, it's a "tragically important" language that is "eating the world." Hate it? Love it? Avoid it? Embrace it?

This talk will be a parade of face-palm JavaScript fails, stupid JavaScript tricks, and bad jokes sure to get an eye-roll from everyone! Along the way, we may even learn a few mistakes to avoid and tips to make our own JavaScript less terrible!

Transcript

12. > const lol = a + b + c – f * ( n + o ); NaN
13. > NaN >= 0 false
14. > NaN <= 0 false
15. > typeof NaN number
16. ( a + b ) + c = a + ( b + c ) // mathematically true > 0.1 + 0.2 === 0.3 false > ( a + b ) + c == a + ( b + c ) ??
17. > 0.1 + 0.2 0.30000000000000004
18. > Math.round(0.4999999999999999722444243843710864894092082) 0 > Math.round(0.4999999999999999722444243843710864894092083) 1 I’ve got 99 problems but JavaScript ain’t 1.0000000000000009
19. > [ 2, 10 ].sort() [ 10, 2 ]
20. > ['10','10','10', '10', '10'].map( parseInt ) [ 10, NaN, 2, 3, 4 ]
21. > typeof undefined // undefined > typeof true // boolean > typeof "hello" // string > typeof 1 // number > typeof {lol:true} // object > typeof [1,2,3] // object > typeof null // object
22. > null == 0 // false > null > 0 // false > null < 0 // false > null >= 0 // true > null <= 0 // true > Number( null ) // 0
23. > false > null > undefined > "" > 0 > NaN
24. > wat.test("javascript"); // true > wat.test("wat r u doin"); // false > const wat = /a/g;
25. // undefined function troll() { return { haha: "ha!" }; } troll(); // automatic semi-colon
26. const arr = []; arr[1] = 1; arr[3] = 2; arr[10] = 3; arr.length // 11 arr[-1] = 4; arr.s = 5; arr.length // 11
96. const user1 = { firstName: "David", lastName: "Neal", address: { street: "123 Main Street", city: "Nashville", state: "Tennessee" } };
97. const user1 = { firstName: "David", lastName: "Neal", address: { street: "123 Main Street", city: "Nashville", state: "Tennessee" } }; const city = user1?.address?.zipCode;
99. const v1 = falseyNullOrUndefined || "defaultValue";
100. const v1 = falseyNullOrUndefined || "defaultValue"; const v2 = onlyNullOrUndefined ?? "defaultValue";
101. globalThis = window ?? self ?? global;
102. Promise.all() –or- Promise.allSettled()
103. let config; if (production) { config = await import("./config.production.js"); } reportBtn.addEventListener("click", async () => { const reporter = await import("./reporter.js); reporter.generateReport(); });
104. const integers = Array.from(html.matchAll(/[0-9]*/g));
105. const big = BigInt(Number.MAX_SAFE_INTEGER); const big2 = 9007199254740991n; const evenBigger = big + 3000000n;
109. To boldly go where NaN has undefined before!
116. Mobile Apps Automation / DevOps Command Line (CLI) Services