The Boolean data type JS

Boolean Boolean data type

Only words denomination; true and false, the digital value two values ​​are not the same, and therefore does not necessarily mean a true and false is not necessarily equal to zero.

To convert to other types of Boolean type

Only 0, NaN, '', null, undefined five values ​​are converted to false, the rest are converted to true (but without any special circumstances)

type of data	Converted to true values	Converted to a value of false
Boolean	true	false
String	Any non-null string	"" Empty string
Number	Any nonzero numeric value (including infinite)	0 sum NaN
Object	Any object	null
Undefined	Not applicable	undefined

Boolean(true) // true
Boolean(false) // false
Boolean('Hello Wolrd') // true
Boolean() // false
Boolean('') // false
Boolean(' ') // true (里面有空格)
Boolean(1) // true
Boolean(0) // false
Boolean(NaN) // false
Boolean({}) // true
Boolean([]) // true
Boolean(null) // false
Boolean(undefined) // false

To convert to other types of Boolean type in three ways:

1. Boolean()
2. !Or !!inverted: first converted to boolean, and then negated
3. Conditional