今天遇到的 node.js 的笔试题，我在解这道题的时候，有个问题我不太明白，感觉自己傻 X 了

function checkLegalStr(str=''){ return (str !== '' && str !== '-' && str !== 'N/A') } function handleObject(obj={}){ for(let key in obj){ if(typeof obj[key] === 'object'){ handleObject(obj[key]); }else if(Array.isArray(obj[key])){ obj[key] = obj[key].filter(item=>{return checkLegalStr(item);}); }else{ if(!checkLegalStr(obj[key])){ delete obj[key]; } } } } const obj = { name: { first: 'Robert', middle: '', last: 'Smith' }, age: 25, DOB: '-', hobbies: [ 'running', 'coding', '-' ], education: { highschool: 'N/A', college: 'Yale' } }; console.log(obj); handleObject(obj); console.log(obj); 

为啥这个结果 obj.hobbies 会有一个空值<1 empty item>

以下是前后输出

{ name: { first: 'Robert', middle: '', last: 'Smith' }, age: 25, DOB: '-', hobbies: [ 'running', 'coding', '-' ], education: { highschool: 'N/A', college: 'Yale' } } { name: { first: 'Robert', last: 'Smith' }, age: 25, hobbies: [ 'running', 'coding', <1 empty item> ], education: { college: 'Yale' } } 

实在是奇怪，我感觉我好水啊，有知道的大哥吗