我在这里添加了一些方法来检查

方法1

if("infiniteScrollEnabled" in localStorage){
     console.log("Item exists in localstorage");
}else{
    console.log("Item does not exist in localstoarge";
}

方法2

if(localStorage.getItem("infiniteScrollEnabled") === null){
    console.log("Item does not exist in localstoarge";
}else{
   console.log("Item exists in localstorage");
}

方法3

if(typeof localStorage["cart"] === "undefined"){
    console.log("Item does not exist in localstoarge";
}else{
   console.log("Item exists in localstorage");
}

方法4

if(localStorage.hasOwnProperty("infiniteScrollEnabled")){
     console.log("Item exists in localstorage");
 }else{
    console.log("Item does not exist in localstoarge";
 }

可以尝试这样做:

 let x = localStorage.getItem('infiniteScrollEnabled') === null ? "not found" : localStorage.getItem('infiniteScrollEnabled')

我在我的项目中使用过，对我来说非常适合

var returnObjName= JSON.parse(localStorage.getItem('ObjName'));
if(returnObjName && Object.keys(returnObjName).length > 0){
   //Exist data in local storage
}else{
  //Non Exist data block
}

localStorage['root2']=null;

localStorage.getItem("root2") === null //false

也许最好先看一遍计划?

localStorage['root1']=187;
187
'root1' in localStorage
true

如果你想检查undefined，你也可以试试这个:

if (localStorage.user === undefined) {
    localStorage.user = "username";
}

getItem是一个方法，如果没有找到value则返回null。

我总是通过检查localStorage或sessionStorage的长度来检查它们是否被设置

if (sessionStorage.length > 0) {
  console.log("exists")
} else {
  console.log("not exists")
}