有什么办法可以避免 localStorage.getItem() 的 key 的未定义值？

Question

There was the following key pair value in my local storage - instrument,BTX(key,value). I deleted the value manually from local storage. Now the value of this key is undefined. I have written this condition to avoid the undefined value, but it is not working. The issue here is that, although the value is undefined so the else block should be executed but here in all possible cases the if block is getting executed.

First way:

if(localStorage.getItem("instrument")){}
else {}

Second way:

if(!!localStorage.getItem("instrument")){}
else {}

Third way:

if(localStorage.getItem("instrument")!==undefined){}
else {}

Answer 1

Try this

if(localStorage.getItem("instrument")!=null){
// Do Something here
}else{
// Do Something Here
}

Hope it's working:)