JS: Boolean Constructor

Boolean(arg)

Force arg to Primitive Value true or false, return it.

console.assert((Boolean(0) === false))
console.assert((Boolean(0.0) === false))
console.assert((Boolean(0.) === false))
console.assert((Boolean(.0) === false))

console.assert((Boolean("") === false))

console.assert((Boolean(null) === false))
console.assert((Boolean(undefined) === false))
console.assert((Boolean(NaN) === false))

// anything else is true
console.assert((Boolean(1)) === true)
console.assert((Boolean(-1)) === true)
console.assert((Boolean(Infinity)) === true)
console.assert((Boolean({})) === true)
console.assert((Boolean([])) === true)
console.assert((Boolean(function () {})) === true)

// Boolean called as a function, returns true/false primitive value
console.assert((typeof Boolean(3)) === "boolean");

new Boolean(arg)

Convert arg to a value that's a boolean object type, return it.

const xx = new Boolean(2);
console.assert((typeof xx) === "object");
console.assert(xx.valueOf() === true);