Useless attempt to make JS == acceptable

Lightweight talk about how we can accept JavaScript's double equals operator in our heart. LOL no.

Transcript

1. (nope nope nope) Useless attempt to make JS == acceptable
2. Hi, I am Hendra @drabiter drabiter.com github.com/drabiter /drabiter /drabiter /drabiter /drabiter /drabiter /drabiter /drabiter /drabiter …..
3. dat pair of ‘=’ equality operator
4. Java’s equality 1 == 1 1 != “1” Object a = new Object(); Object b = new Object(); // false a == b Compare the reference!
5. Ruby’s equality # all true 1 == 1 ‘a’ == ‘a’ (2-1) == 1 1 != ‘1’ [] == [] {} == {} {} != {:a => 1}
6. Brainfuck’s equality [] i love the only zero
7. Javascript’s equality // looks fine true == true false == false 5 == 5 0 != 1 ‘foo’ == ‘foo’
8. Javascript’s equality // ...until we mix’em 2 == ‘2’ ‘9’== 9 okay, maybe this is about what written...
9. Javascript’s equality // ...but now 1 == [1] ‘1’ == [1] [1] != [1] ‘’ == [] WTF
10. Javascript’s quiz [[]] != ‘’ [[]] != ‘0’ [[]] == [] [4] != 4 [7,7] == ‘7, 7’ [1,2] == ‘1,2’ [[1,2],3] == ‘[1,2],3’ [0,-0] == ‘0,-0’ false true false false false true false false
11. ???
12. just use the threesome equal === USELESS
13. because someone did bring it up then why?
14. http://dorey.github.io/JavaScript-Equality-Table/
15. http://strilanc.com/visualization/2014/03/27/Better-JS-Equality-Table.html
16. “Use three equals unless you fully understand the conversions that take place for two-equals.”
17. ssst we’re already know that conversion happened
18. it should be like this
19. NaN is not NaN > typeof(6) ‘number’ > typeof(NaN) ‘number’ > NaN == NaN false > NaN === NaN false it also won’t be equal to other types
21. object too > foo = {a:1, b:2} > bar = {a:1, b:2} > foo == {a:1, b:2} false > foo == bar false > {a:1, b:2} == {a:1, b:2} false
23. when possible, parseInt(string) ‘1’ == 1 ‘-10’ == -10 ‘8a’ != 8 21 == ‘2’ + ‘1’ ‘32’ == 16 * 2 -1 != ‘1’ ‘’ == 0
25. true ⇔ 1 false ⇔ 0 TRUE only equals to number 1 > true == 1 > true != 5 > true == Infinity FALSE only equals to number 0 > false == 0 > false != -5 > false != -Infinity
27. Array#toString() > [1] == ‘1’ // so, [1] == 1 > [‘1’] == ‘1’ // so, [‘1’] == 1 > [] == ‘’ > [] == 0 > [] != [] > [[]].toString() // ‘’ > [].toString() // ‘’
29. but, use Array#valueOf() for array > [1].valueOf() // [ 1 ] > [‘1’].valueOf() // [ ‘1’ ] > [].valueOf() // [] > [[]].valueOf() // [ [] ] // not deep equal > [0] != [0] > [] != [] > [‘3’] != [‘3’]
31. null == undefined typeof(undefined) // ‘undefined’ value for declared but has not yet be assigned a value typeof(null) // ‘object’ null is considered a placeholder for an object - representing no value
32. null == undefined “This was actually an error in the original JavaScript implementation that was then copied in ECMAScript” - Professional JavaScript for Web Developers
34. the rest are straightforward unparseable string only equals with the same ‘abc’ == ‘abc’ Infinity is simply constant of a number Infinity == Infinity Infinity == (-Infinity * -1)
36. NaN (NaN Ain’t NaN) not deep equal object-object & array-array parseInt string when possible use toString() to array when meet non-array null == undefined (and use well-known rules / common sense) ;)
37. Thank you!