Javascript 如何检查对象是否具有属性javascript？
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How to check if object has property javascript?
提问by Michael
I have this function:
我有这个功能：
function ddd(object) {
if (object.id !== null) {
//do something...
}
}
But I get this error:
但我收到此错误：
Cannot read property 'id' of null
How can I check if object has property and to check the property value??
如何检查对象是否具有属性并检查属性值？
回答by deltree
hasOwnPropertyis the method you're looking for
hasOwnProperty是你正在寻找的方法
if (object.hasOwnProperty('id')) {
// do stuff
}
As an alternative, you can do something like:
作为替代方案，您可以执行以下操作：
if (typeof object.id !== 'undefined') {
// note that the variable is defined, but could still be 'null'
}
In this particular case, the error you're seeing suggests that objectis null, not idso be wary of that scenario.
在这种特殊情况下，您看到的错误表明它object为空，不要id对这种情况保持警惕。
For testing awkward deeply nested properties of various things like this, I use brototype.
为了测试像这样的各种东西的笨拙的深度嵌套属性，我使用了brototype。
