我如何检查一个项目是否设置在localStorage?目前我正在使用
if (!(localStorage.getItem("infiniteScrollEnabled") == true || localStorage.getItem("infiniteScrollEnabled") == false)) {
// init variable/set default variable for item
localStorage.setItem("infiniteScrollEnabled", true);
}
当前回答
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
其他回答
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。
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
可以尝试这样做:
let x = localStorage.getItem('infiniteScrollEnabled') === null ? "not found" : localStorage.getItem('infiniteScrollEnabled')
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";
}
你可以使用hasOwnProperty方法来检查
> localStorage.setItem('foo', 123)
undefined
> localStorage.hasOwnProperty('foo')
true
> localStorage.hasOwnProperty('bar')
false
适用于当前版本的Chrome(Mac)， Firefox(Mac)和Safari。
