Question

我有一个包含用户和点列表的json文件。我想以某种方式循环直到_id == userId，然后计算有多少对象来获取它们的位置。

到目前为止，我已经有了这个json文件，其中包含了desc顺序中的点

[  
  {  
    "_id":"55db8684ce3bf55b4b612a72",
    "firstname":"Billy",
    "lastname":"Bob",
    "points":3109373
  },
  {  
    "_id":"55dbdffeaba8ee274d3b9f89",
    "firstname":"Steve",
    "lastname":"Jones",
    "points":34434
  },
  {  
    "_id":"55dbdbf756b0fa064dd3e507",
    "firstname":"Jim",
    "lastname":"Kirk",
    "points":1000
  },
  {  
    "_id":"55dbdc2756b0fa064dd3e508",
    "firstname":"Casey",
    "lastname":"Jones",
    "points":36
  },
  {  
    "_id":"55dbdbd656b0fa064dd3e506",
    "firstname":"Reg",
    "lastname":"Barclay",
    "points":33
  },

]

我需要做的是使用他们的ID找到用户的位置。到目前为止，我的位置总是返回undefined。

$.each(obj, function(index, value) {    

       var returnObj = (this === "<%= user._id %>"); 
       var position = returnObj.length;
       console.log('user position is ' + position);

});

但是这总是返回未定义的11次，这就是位置应该是什么。

Answer 1

如果我找到了你，那么使用for代替each可以使用更快，编码也不多的代码。

试试这个，

for(var i =0;i < obj.length; i++)
{
  if(obj[i]['_id'] == "55dbdc2756b0fa064dd3e508"){
     alert('position :' +  parseInt(i + 1));  //<--position in an obj
     alert('index :' + i); //<----actual index
     break;
  }
}

var obj=[  
  {  
    "_id":"55db8684ce3bf55b4b612a72",
    "firstname":"Billy",
    "lastname":"Bob",
    "points":3109373
  },
  {  
    "_id":"55dbdffeaba8ee274d3b9f89",
    "firstname":"Steve",
    "lastname":"Jones",
    "points":34434
  },
  {  
    "_id":"55dbdbf756b0fa064dd3e507",
    "firstname":"Jim",
    "lastname":"Kirk",
    "points":1000
  },
  {  
    "_id":"55dbdc2756b0fa064dd3e508",
    "firstname":"Casey",
    "lastname":"Jones",
    "points":36
  },
  {  
    "_id":"55dbdbd656b0fa064dd3e506",
    "firstname":"Reg",
    "lastname":"Barclay",
    "points":33
  },

]


for(var i =0;i < obj.length; i++)
{
    if(obj[i]['_id'] == "55dbdc2756b0fa064dd3e508"){
       alert('position :' +  parseInt(i + 1));
       alert('index :' + i);
       break;
    }
}

循环JSON并在满足条件时停止。然后计算对象

1 个答案: