js 判断对象为空三板斧

let obj = {}


let k = ''
for (k in obj) { }
if (!k) {
    console.log('空对象');
} else {
    console.log('非空对象');
}


let num = Object.keys(obj).length
if (num) {
    console.log('非空对象');
} else {
    console.log('空对象');
}


let str = JSON.stringify(obj)
if (str === '{}') {
    console.log('空对象');
} else {
    console.log('非空对象');
}