javascript-gotchas.md

JavaScript gotchas!

TimeOut Sort

var numbers = [38, 43, 33, 43, 27, 20, 33, 17, 49, 11, 30, 27, 35, 42, 14, 32, 44, 44, 16, 44];

numbers.forEach(function (number) {
    (function (number) {
        setTimeout(function () {
            console.log(number)
        }, number);
    }(number));
});

https://codepen.io/Bigismall/pen/QgEyoY

Automatic type conversion

console.log([1,5,20,10].sort()) //[ 1, 10, 20, 5 ]

https://codepen.io/Bigismall/pen/gRMPye

Are the numbers equal?

var a = 0.1,
    b = 0.2,
    c = 0.3;

console.log((a + b) === c);    //false

var a = 0 * 1,
    b = 0 * -1;

console.log(a, b);      //0 -0
console.log(a === b);   //true
console.log(1/a === 1/b);   //false

https://codepen.io/Bigismall/pen/XgKXwb

To string evaluation

var a = 1,
    b = "2",
    c = a + b,
    d = b + a,
    e = (b + b) * 1,
    f = a + a;

console.log(c, typeof c);   // 12 string
console.log(d, typeof d);   // 21 string
console.log(e, typeof e);   // 22 number
console.log(f, typeof f);   // 2 number

https://codepen.io/Bigismall/pen/OgXMYE

Type of trap

typeof {} === "object" //true
typeof "" === "string" //true
typeof [] === "array"; //false

https://codepen.io/Bigismall/pen/gRMPNz

Math min and max values

console.log(Math.max()); // -Infinity
console.log(Math.min()); // Infinity

https://codepen.io/Bigismall/pen/dRXGxR

Also

• http://www.jazcash.com/a-javascript-journey-with-only-six-characters/
• http://js1k.com
• https://www.chromeexperiments.com/demoscene
• https://aframe.io/
• http://phaser.io/examples
• https://www.nativescript.org/
• http://piqnt.com/planck.js/
• http://www.geo-fs.com/
• http://voxeljs.com/
• https://www.codingame.com/start
• http://codeincomplete.com/games/
• https://threejs.org/