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
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
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。
您应该在localStorage中检查项目的类型
if(localStorage.token !== null) {
// this will only work if the token is set in the localStorage
}
if(typeof localStorage.token !== 'undefined') {
// do something with token
}
if(typeof localStorage.token === 'undefined') {
// token doesn't exist in the localStorage, maybe set it?
}
WebStorage规范中的getItem方法，如果项不存在，则显式返回null:
．.． 如果给定的键在与该对象关联的列表中不存在，则该方法必须返回null. ...
所以，你可以:
if (localStorage.getItem("infiniteScrollEnabled") === null) {
//...
}
请看这个相关问题:
在HTML5 localStorage中存储对象
