javascript - Json 错误：无法读取未定义的属性“xxx”

Question

我正在获得这样的@attr 值：

item['@attr']['nowplaying']

当属性存在于 json 中时，这可以正常工作，但如果它不存在，我会收到错误消息：

Uncaught TypeError: Cannot read property 'nowplaying' of undefined 

我怎样才能避免这个错误？

Answer 1

if (item['@attr']){
    var nowPlaying = item['@attr']['nowplaying']);
}

Answer 2

Test to see if item['@attr'] has a value that can have properties before you try to access any properties of it.

if (item['@attr']) {
   whatever(item['@attr']['nowplaying']);
}