var a = "12"
var b = new String("12")
a // "12"
b // String {"12"}
a == b // true (a is compared with b's toPrimitive value)
// b's primitive value is obtained by calling toString()
Amy Simmons amysimmons
amysimmons
/ object-loose-equality.md
Created
February 21, 2018 08:49
amysimmons
/ equality-loose-booleans.md
Created
February 20, 2018 08:53
"22" == true // false
"22" == 1 // false
22 == 1 // false
amysimmons
/ string-to-number-implicit.md
Last active
February 19, 2018 08:21
"2" - 0 // 2
"2" / 1 // 2
"2" * 1 // 2
amysimmons
/ num-string-explicit.md
Created
February 14, 2018 08:52
a = { valueOf: () => 22, toString: () => 44 }
String(a) // "44"
a + "" // "22"
amysimmons
/ parseInt.md
Created
February 9, 2018 08:07
parseInt('22px') // 22
Number('22px') // NaN
amysimmons
/ date-number.md
Last active
February 8, 2018 18:55
// use for getting a specific (non-now) time
x = new Date().getTime() // 1518116090213
// use for getting the current time
y = Date.now() // 1518115963826
amysimmons
/ falsy-objects.md
Created
February 7, 2018 08:30
document.all // HTMLAllCollection(224) [html, head, meta, …]
Boolean(document.all) // false
amysimmons
/ falsy.md
Last active
February 7, 2018 08:27
// falsy values
Boolean(undefined) // false
Boolean(null) // false
Boolean(NaN) // false
Boolean(-0) // false
Boolean(+0) // false
Boolean("") // false
// everything else is truthy
amysimmons
/ to-number-complex.md
Created
February 6, 2018 09:10
x = {}
x.valueOf = () => 22
Number(x) // 22
y = []
y.toString = () => '22'
Number(y) // 22
z = {}
amysimmons
/ to-number-simple.md
Created
February 6, 2018 08:57
Number(null) // 0
Number(undefined) // NaN
Number(true) // 1
Number(false) // 0
Number(22) // 22
Number("hello") // NaN
Number("0") // 0