我有一个JSON对象，由AJAX请求返回，我有一些问题与.length，因为它一直返回未定义。只是想知道我是否用对了:
console.log(data.length);
console.log(data.phones.length);
它们都返回undefined，尽管它们是有效的对象。
更新: 返回的JSON对象示例:
{"reqStatus":true,"phones":{"one":{"number":"XXXXXXXXXX","type":"mobile"},"two":{"number":"XXXXXXXXXX","type":"mobile"}}}
当前回答
你不需要改变JSON格式。
替换:
console.log(data.phones.length);
:
console.log( Object.keys( data.phones ).length ) ;
其他回答
您的问题是，电话对象没有长度属性(除非您在返回的JSON中定义了它)，因为对象与数组不相同，即使用作关联数组。如果电话对象是一个数组，它将有一个长度。你有两个选择(也许更多)。
Change your JSON structure (assuming this is possible) so that 'phones' becomes "phones":[{"number":"XXXXXXXXXX","type":"mobile"},{"number":"XXXXXXXXXX","type":"mobile"}] (note there is no word-numbered identifier for each phone as they are returned in a 0-indexed array). In this response phones.length will be valid. Iterate through the objects contained within your phones object and count them as you go, e.g. var key, count = 0; for(key in data.phones) { if(data.phones.hasOwnProperty(key)) { count++; } }
如果你只针对新的浏览器，选项2可能是这样的
你不需要改变JSON格式。
替换:
console.log(data.phones.length);
:
console.log( Object.keys( data.phones ).length ) ;
考虑使用underscore.js。它将允许你检查大小，如:
var data = {one : 1, two : 2, three : 3};
_.size(data);
//=> 3
_.keys(data);
//=> ["one", "two", "three"]
_.keys(data).length;
//=> 3
var json=[{"id":"431","code":"0.85.PSFR01215","price":"2457.77","volume":"23.0","total":"565.29"},{"id":"430","code":"0.85.PSFR00608","price":"1752.45","volume":"4.0","total":"70.1"},{"id":"429","code":"0.84.SMAB00060","price":"4147.5","volume":"2.0","total":"82.95"},{"id":"428","code":"0.84.SMAB00050","price":"4077.5","volume":"3.0","total":"122.32"}]
var obj = JSON.parse(json);
var length = Object.keys(obj).length; //you get length json result 4
你可以用这样的东西
var myObject = {'name'：'Kasun'， 'address'：'columbo'，'age'： '29'} var count = Object.keys（myObject）.length; 控制台.log（计数）;
