by @peferron
JS is an implementation of the ECMAScript standard.
| ECMAScript 3 (1999) | Last version supported by IE8 |
| ECMAScript 5 (2009) | Modern JS |
| ECMAScript 2015 | |
| ECMAScript 2016 |
Client-side: Windows XP support ended in April 2014.
Server-side: Node uses a modern JS engine (V8).
Can compile to older ES versions with Babel.
Suggest days with nice weather for visiting San Francisco.
Written in ECMAScript 3.
We will update it to ECMAScript 2016 together.
HTTP GET sf-forecast.json
Open app.js in text editor.
And others.
Open app.js and replace for loops with Array methods.
But arrow functions work out of the box.
Awkward workarounds exist:
This should work:
This should work:
But it doesn't.
Uncaught TypeError: Cannot read property 'name' of undefinedOpen app.js and replace function with =>.
Open app.js and replace string concatenation with interpolation.
Uses Promises instead of callbacks.
Open app.js and replace XMLHttpRequest with fetch.
Open app.js and replace callbacks with async / await.
How to make maximum humidity and minimum temperature configurable?
async function getLovelyDays(maxHumidity, minTemperature) {
...
}
var lovelyDays = await getLovelyDays(75, 80);
Unreadable for someone not familiar with the code.
This line was in our app before we moved to fetch.
Can you infer what true means?
request.open('GET', 'sf-forecast.json', true);
And now?
request.open('GET', 'sf-forecast.json', {async: true});
Open app.js and add the options maxHumidity and minTemperature.
Open app.js and make options default to {}.
Deeply nested patterns are supported, but can hurt readability. Use responsibly.
Open app.js and use destructuring with default values for maxHumidity and minTemperature.