如何将对象检索到Javascript中的数组？

Question

我目前正在练习js中的一些基本问题，并且对这些语言中的任何一种都是比较新的。如果另一个obj“third”具有相同的属性值，我想从属性“second”中将属性的值和名称检索到数组“temp”中。 我可以做到这一点，当属性名称已经定义，但我怎么能做到这一点，如果我不知道实际的属性名称。可使用Object.keys（）

我的代码是这样的：

 function where(second, third) { 
    var arr = []; 
    var temp=[]; 
    for(var i in second) 
    { 

     if(third.hasOwnProperty('last')){ 
     if(second[i].last===third.last){ 
      arr=second[i]; 
      temp.push(arr); 
     } 
     } 
     if(third.hasOwnProperty('first')){ 
     if(second[i].first===third.first){ 
      arr=second[i]; 
      temp.push(arr); 
     } 
     } 

    } 
    return temp; 
} 

where([{ first: 'Ram', last: 'Ktm' }, { first: 'Sam', last: null }, { first: 'Tybalt', last: 'Capulet' }], { last: 'Capulet' }); 

结果数组是：[{ 'first': 'Tybalt', 'last': 'Capulet' }]

我怎样才能获得相同的结果，即使我不知道实际的属性名称。例如，这里的名字首先和最后可能是食物，而其用途是未知的。 我已经在这里使用了以下线程。

[2]: https://stackoverflow.com/questions/4607991/javascript-transform-object-into-array

[1]: https://stackoverflow.com/questions/4607991/javascript-transform-object-into-array

Answer 1

function where(second, third) { 
    var temp = []; 
    var k = Object.keys(third)[0]; // expecting only one element! 
    second.forEach(function (obj) { 
     if (obj[k] === third[k]) { 
      temp.push(obj); 
     } 
    }); 
    return temp; 
} 

Answer 2

function where(second, third) { 
    var tmp = []; 
    var length = second.length; 

    var i, k, test; 
    // Go through second's each item to see that... 
    for (i = 0; i < length; ++i) { 
    test = second[i]; 
    // For all key in third that belongs to third (not inherited or else) 
    for (k in third) { 
     // Check has own property. 
     if (!third.hasOwnProperty(k)) { 
     continue; 
     } 
     // If second[i] don't have key `k` in second or second[i][k]'s value is 
     // not equal to third[k], then don't put it into tmp, start to check next. 
     if (!third.hasOwnProperty(k)) { 
     break; 
     } else if (test[k] !== third[k]) { 
     break; 
     } 
     tmp.push(test); 
    } 
    } 
    return tmp; 
} 

Answer 3

我觉得getOwnPropertyName是你在找什么。 https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyNames

Object.getOwnPropertyNames({a:1,2:"b",c:"a"}).sort() // returns Array [ "2", "a", "c" ] 

我会在最初的回答扩大

var temp = []; 

var myobj = [{cat:"Felix",dog:"Milo",bird:"Monkey",3:"pets"}, 
     {cat:"Wiskers",dog:"yapper",bird:"tweeter",1:"human"}]; 

var myobj2 = {cat:"Harry",dog:"Fuzz",1:"human"}; 

var objKeys = Object.getOwnPropertyNames(myobj); //will have key "1" that matches below 

objKeys.forEach(function(key) { 
    if(myobj2.hasOwnProperty(key)) { 
     temp.push(myobj2[key]) // will push "human" to temp array 
    } 
})