获取JQuery对象中的属性数量 [英] Getting the number of properties in JQuery object

问题描述

我试图找出以下对象中有多少个属性.显然，我可以看到2，但是我需要动态地了解.

I'm trying to figure out how many properties are in the following object. Obviously, I can see 2, but I need to know dynamically.

var test = $.parseJSON('{ "ddSize": "Size", "ddColor": "Color" }');

如果我尝试:

var mylen = test.length;

.length未定义.该对象中的属性数量将改变.有时是1，有时是2或3，但是我只是想不出如何测试它.

.length is undefined. The number of properties in this object will change. Sometimes it's 1, sometimes 2 or 3, but I just can't figure out how to test it.

推荐答案

这是一个JavaScript JSON对象. length功能不可用.

This is a JavaScript JSON object. length function is not available.

第一个使用纯JavaScript的解决方案:

First solution with pure JavaScript:

var data = $.parseJSON('{ "ddSize": "Size", "ddColor": "Color" }'); 
var keys = [];
for (key in data) {
  keys.push(key);
}
// numberOfKeys should equal to 2
var numberOfKeys = keys.length;

第二种解决方案，如果您喜欢jQuery:

Second solution if you prefer jQuery:

var data = $.parseJSON('{ "ddSize": "Size", "ddColor": "Color" }');
var keys = [];
$.each(data, function(key, value) {
  keys.push(key)
});
// numberOfKeys should equal to 2
var numberOfKeys = keys.length;

jQuery.each函数的文档

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