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
最短的方法是使用默认值，如果key不在存储中:
var sValue = localStorage['my.token'] || ''; /* for strings */
var iValue = localStorage['my.token'] || 0; /* for integers */
其他回答
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";
}
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
最短的方法是使用默认值，如果key不在存储中:
var sValue = localStorage['my.token'] || ''; /* for strings */
var iValue = localStorage['my.token'] || 0; /* for integers */
正如@Christian C. Salvadó上面提到的，你可以做到 If (xxx === null){}
但是null也是一个假值，就像这样:
if (null){
console.log ("hello");
}
它不打印“hello”。
如何测试localStorage中存在的项? 此方法适用于Internet explorer。
<script>
try{
localStorage.getItem("username");
}catch(e){
alert("we are in catch "+e.print);
}
</script>
