获取对象中数组的大小

Question

我希望在对象中获取数组的大小有一些帮助:

var st = { "itema":{...},"itemb":[{"id":"s01","cd":"c01","dd":"d01",....}{"id":"s02","cd":"c02","dd":"d02",....}]}

你如何得到内部物体的数量"itemb"(在这种情况下为2)？

Answer 1

Javascript数组具有length属性.像这样使用它:

st.itemb.length

Answer 2

数组有一个.length返回元素数的属性.

var st =
    {
        "itema":{},
        "itemb":
        [
            {"id":"s01","cd":"c01","dd":"d01"},
            {"id":"s02","cd":"c02","dd":"d02"}
        ]
    };

st.itemb.length // 2