合并javascript中的两个对象，忽略未定义的值

Question

我必须合并两个对象，但我不想将未定义的值分配给已定义的值。

A = { activity: 'purchased', count: undefined, time: '09:05:33' }
B = { activity: 'purchased', count: '51', time: undefined }

当我尝试 Object.assign 时，未定义正在替换具有值的字段。

我想要的是

C = { activity: 'purchased', count: '51', time: '09:05:33' }

Answer 1

let A = { activity: 'purchased', count: undefined, time: '09:05:33' }
let B = { activity: 'purchased', count: '51', time: undefined }

let C={}
Object.keys({...A,...B}).map(key=>{
C[key]=B[key]||A[key]
})
console.log(C)