JSON.stringify(value)
JSON.stringify(value, replacer)
JSON.stringify(value, replacer, space)

console.log(JSON.stringify({ x: 5, y: 6 }))
// Expected output: '{"x":5,"y":6}'
 
console.log(JSON.stringify([new Number(3), new String('false'), new Boolean(false)]))
// Expected output: '[3,"false",false]'
 
console.log(JSON.stringify({ x: [10, undefined, function () {}, Symbol('')] }))
// Expected output: '{"x":[10,null,null,null]}'
 
console.log(JSON.stringify(new Date(2006, 0, 2, 15, 4, 5)))
// Expected output: '"2006-01-02T15:04:05.000Z"'