javascript - 在 JSON 对象中搜索特定键

Question

我目前正在尝试遍历一个看起来像这样的 JSON 对象：

"coupons":{
    "item1":{
         "id":"155",
         "name":"First Item",
         "value":-5199.6
    },
    "item2":{
         "id":"255",
         "name":"Second Item",
         "value":-424.91
    }
}

我想返回每个项目 id 的值。我怎样才能做到这一点？

我正在用 JS 编程。

谢谢！

Answer 1

var coupons = {
    "item1":{
         "id":"155",
         "name":"First Item",
         "value":-5199.6
    },
    "item2":{
         "id":"255",
         "name":"Second Item",
         "value":-424.91
    }
}

var ids = [];
for(var item in coupons) {
    ids.push(coupons[item]['id']);
}

console.log(ids);

Answer 2

You can use DefiantJS (http://defiantjs.com), which enables you to search a JSON structure with XPath queries. This lib extends the global object JSON with the method "search" and returns an array with the matches, if any (empty array, i no matches were found).

XPath is a standardised query language and pretty easy the grasp. Here is a testing tool with examples; http://defiantjs.com/#xpath_evaluator

Check out this working fiddle;
http://jsfiddle.net/hbi99/Yc6cc/

var data = {
    ...
},
res = JSON.search( data, '//*[id]' ),
str = '';

for (var i=0; i<res.length; i++) {
    str += res[i].id +' : '+ res[i].name +'<br/>';
}

document.getElementById('output').innerHTML = str;

Answer 3

var obj = { 'json...' };

for (var key in obj)
{
    var item = obj[key];
    alert("id is " + item.id);
}

您可以使用var .. in obj语法来迭代任何对象的属性（或关联索引；在 JS 中相同）。始终注意您了解正在迭代的对象，因为某些对象（例如数组）具有您希望避免迭代的其他属性。

Answer 4

每个coupons[k]都是项目，你可以使用coupons[k].id

var coupons = {
    "item1":{
         "id":"155",
         "name":"First Item",
         "value":-5199.6
    },
    "item2":{
         "id":"255",
         "name":"Second Item",
         "value":-424.91
    }
}

for(var k in coupons){
      console.log(coupons[k].id);

}

Answer 5

I would suggest something like:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js"></script>
<script>
var dataset = {
                "coupons":{
                    "item1":{
                         "id":"155",
                         "name":"First Item",
                         "value":-5199.6
                    },
                    "item2":{
                         "id":"255",
                         "name":"Second Item",
                         "value":-424.91
                    }
                }
            }

$(document).ready(function(){

    $.each(dataset.coupons, function(i, item) {
        $("#data").append('<p>' + item.id + '</p>'); 
        $("#data").append('<p>' + item.name + '</p>'); 
        $("#data").append('<p>' + item.value + '</p>'); }
    );

});

</script>
<div id="contentC"></div>