使用JSON.parse（），如何在多维数组中取值？

Question

Before use JSON.parse, an JSON array is shown below:

var temp = {
      "queries": [
    {
      "sample_size": 3,
      "results": [
        {
          "name": "temperature",
          "tags": {
            "Tag": [
              "temperature"
            ]
           },
           "values": [
            [
              1452221580000,
              27.5
            ],
            [
              1452221640000,
              27.1
            ],
            [
              1452221700000,
              27.3
            ]
           ]
        ]}
     ]}
    }

I need to get the value from the array, so I use JSON.parse().

var jsonparse_temp = JSON.parse(temp);
var dataNum = jsonparse_temp ['queries']['sample_size'];
var timestamp1 = jsonparse_temp ['queries']['results']['value'][0][0]
var value1 = jsonparse_temp ['queries']['results']['value'][0][1]

After that, is value1 equal 27.5 ? I'm not sure this way could sign the value to variable.

Answer 1

It's not a JSON string it's a well-formed object no need to parse it. There is nested array so you need to get the object element from the array using the index.

 var temp = { "queries": [{ "sample_size": 3, "results": [{ "name": "temperature", "tags": { "Tag": [ "temperature" ] }, "values": [ [ 1452221580000, 27.5 ], [ 1452221640000, 27.1 ], [ 1452221700000, 27.3 ] ] }] }] }; // using bracket notation var dataNum = temp['queries'][0]['sample_size']; var timestamp1 = temp['queries'][0]['results'][0]['values'][0][0] var value1 = temp['queries'][0]['results'][0]['values'][0][1]; console.log(dataNum, timestamp1, value1); // using dot notation var dataNum1 = temp.queries[0].sample_size; var timestamp11 = temp.queries[0].results[0].values[0][0] var value11 = temp.queries[0].results[0].values[0][1]; console.log(dataNum1, timestamp11, value11); 

Answer 2

an JSON array is shown below:

That isn't JSON. That is a JavaScript object. There is no JSON anywhere in your question.

 var jsonparse_temp = JSON.parse(temp); 

This will return undefined since temp is not a string of JSON.

 ['queries']['sample_size']; 

queries is an array, not an object. It doesn't have a sample_size property.

The first value in that array is an object which does have that property.

You need to access each level of the data structure in order. You can't skip levels.

var dataNum = temp.queries[0].sample_size;

Answer 3

change your code to this:

 var dataNum = temp['queries']['sample_size']; var timestamp1 = temp['queries']['results']['value'][0][0] var value1 = temp['queries']['results']['value'][0][1]