Maar denk eens verder. Gaan we de wereld beter maken door verder te groeien? Dat willen ondernemers. En daar zijn neveneffecten aan verbonden. Uber is zogenaamd idealistisch. Ze willen de klant een betere en goedkopere taxirit bieden, maar hun chauffeurs worden uitgebuit. Met Airbnb kun je een leuk zakcentje verdienen, maar woonwijken worden hotels zonder sociale patronen. Facebook is één grote fake-news-show. Amazon is zo goedkoop dat ze alle kleine ondernemers van de weg drukken. Musk wil ons naar Mars brengen. Dat gaat zeker gebeuren, maar wat gaan we daar doen? Maakt het ons gelukkig? Waarom kiezen we er niet voor om elkaar en onze natuur op deze planeet vooruit te helpen?

Airbnb lets people rent out part or all of their homes for short stays,

Contrast that with an idea that came to me about five years ago. A young man by the name of Brian Chesky came up to me and had this idea that he was going to have an air mattress in his apartment that he rented to people. It would be an air bed and breakfast and I immediately thought: wow, that’s a horrible, horrible idea. Who would want to rent an air mattress out to somebody’s apartment like probably a serial killer?

Sometimes you want to introduce a new variable scope—for example, to prevent a variable from becoming global. In JavaScript, you can’t use a block to do so; you must use a function.

(function () { // open IIFE var tmp = ...; // not a global variable }()); // close IIFE

// bad
(function () {
   var tmp = ...;
   ...
})());

// good
{
  const tmp = ...;
  ...
}

for (var i=0; i < 5; i++) { (function () { var i2 = i; // copy current i result.push(function () { return i2 }); }()); }

// bad
for (var i=0; i < 5; i++) {
    (function () {
        var i2 = i; // copy current i
        result.push(function () { return i2 });
    }());
}

// good
for (let i=0; i < 5; i++) {
    // copy current i
    const i2 = i;
    result.push(() => i2);
}

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function

This chapter is about “Basic JavaScript,”

Math.pow

Math.pow

function

function

Function expressions are often used as arguments in function calls in JavaScript. Always be careful when you refer to this from one of those function expressions.

First, we could store this in a different variable:logHiToFriends: function () { 'use strict'; var that = this; this.friends.forEach(function (friend) { console.log(that.name+' says hi to '+friend); }); }

Every function has its own special variable this. This is inconvenient if you nest a function inside a method, because you can’t access the method’s this from the function

This section does not fully explain how JavaScript inheritance works, but it shows you a simple pattern to get you started. Consult Chapter 17 if you want to know more.In addition to being “real” functions and methods, functions play another role in JavaScript: they become constructors—factories for objects—if invoked via the new operator. Constructors are thus a rough analog to classes in other languages. By convention, the names of constructors start with capital letters. For example:// Set up instance data function Point(x, y) { this.x = x; this.y = y; } // Methods Point.prototype.dist = function () { return Math.sqrt(this.x*this.x + this.y*this.y); };We can see that a constructor has two parts. First, the function Point sets up the instance data. Second, the property Point.prototype contains an object with the methods. The former data is specific to each instance, while the latter data is shared among all instances.To use Point, we invoke it via the new operator:> var p = new Point(3, 5); > p.x 3 > p.dist() 5.830951894845301p is an instance of Point:> p instanceof Point true

Variables Are Function-ScopedThe scope of a variable is always the complete function (as opposed to the current block). For example:function foo() { var x = -512; if (x < 0) { // (1) var tmp = -x; ... } console.log(tmp); // 512 }We can see that the variable tmp is not restricted to the block starting in line (1); it exists until the end of the function.

var

In JavaScript, you declare variables via var before using them:> var x; > x undefined > y ReferenceError: y is not defined

var

You can declare and initialize several variables with a single var statement:var x = 1, y = 2, z = 3;

function

function

var

To concatenate strings in multiple steps, use the += operator:> var str = ''; > str += 'Multiple '; > str += 'pieces '; > str += 'are concatenated.';

'You have ' + messageCount + ' messages'

"That's nice!"

"Did she say \"Hello\"?"

== and !=

==, !=

Increment: ++variable, variable++ Decrement: --variable, variable--

Binary logical operators: && (And), || (Or)

Boolean(), called as a function, converts its parameter to a boolean. You can use it to test how a value is interpreted:> Boolean(undefined) false > Boolean(0) false > Boolean(3) true > Boolean({}) // empty object true > Boolean([]) // empty array true

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"abc"

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// single-line comment

Thanks to Airbnb, everyone can find that affordable night's sleep, and anyone can become a landlord. But there's more to renting out your extra space than making some cash, meeting interesting people, and then watching them slowly succumb to your H.H. Holmes-inspired hostel of horrors. There are, of course, taxes to consider.

The benefits that Airbnb and Uber pioneered go beyond convenience. They allow people to make human connections in an era that has become much more institutionalized in the decades since family-run bed-and-breakfasts began being replaced by standardized hotel chains.

Automated Machine Learning — A Paradigm Shift That Accelerates Data Scientist Productivity @ Airbnb

The listing represented an extraordinary opportunity in American history, one facilitated by both modern technology and a president with a large real estate portfolio: a chance for travelers to book a room in a building housing the president’s family — one of the most secure buildings in New York City, if not the world — with nothing more than the click of a mouse.