JS: Boolean Constructor
Boolean(arg)
-
Force arg to Primitive Value
true
orfalse
, return it.console.log(Boolean(0) === false) console.log(Boolean(0.0) === false) console.log(Boolean(0.) === false) console.log(Boolean(.0) === false) console.log(Boolean("") === false) console.log(Boolean(null) === false) console.log(Boolean(undefined) === false) console.log(Boolean(NaN) === false) // anything else is true console.log(Boolean(1)) console.log(Boolean(-1)) console.log(Boolean(Infinity)) console.log(Boolean({})) console.log(Boolean([])) console.log(Boolean(function () {}))
// Boolean called as a function, returns true/false primitive value console.log((typeof Boolean(3)) === "boolean")
new Boolean(arg)
-
Convert arg to a value that's a boolean object type, return it.
let xx = new Boolean(2) console.log((typeof xx) === "object") console.log(xx.valueOf() === true)