JSFiddle - React, Tailwind, and code Playground
JavaScript
const obj = {
'undefined': undefined,
'null': null,
'zero': 0,
'one': 1,
'symbol': Symbol('symbol')
};
const properties = ['test', 'one', 'symbol', 'null', 'zero', 'undefined', 'toString'];
const printResult = (obj, prop) => {
console.log(`
---Testing ${prop} in ${JSON.stringify(obj)}---
undefined : ${undefined !== obj[prop]}
void : ${void(0) !== obj[prop]}
truthy : ${!!obj[prop]}
typeof : ${'undefined' !== typeof obj[prop]}
in : ${prop in obj}
hasOwnProperty : ${obj.hasOwnProperty(prop)}
`);
}
properties.forEach(val => printResult(obj, val));