Question

如何检查本地存储空值是否为空？例如......

localStorage.setItem('favoriteflavor','');

var taste = localStorage.getItem('favoriteflavor');

if(taste == null){
   console.log('favoriteflavor is null');
} 
else {
   console.log('favoriteflavor is NOT null');
}

这是最有意义的，但我没有得到任何结果。我也试过这个..

 if(localStorage['favoriteflavor'] == 'null'){ 
   console.log('favoriteflavor is null');
 }

http://jsfiddle.net/AwsyE/6/

Answer 1

如果将favoriteflavor设置为空字符串，那么您应该检查它是否为空字符串

localStorage.setItem('favoriteflavor','');
var taste = localStorage.getItem('favoriteflavor');
if(taste == ''){
   console.log('favoriteflavor is empty');    
}
else{
   console.log('favoriteflavor is NOT empty');
}

或者，如果您要删除favoriteflavor，那么您可以将其检查为空

localStorage.setItem('favoriteflavor','chocolate');
delete localStorage['favoriteflavor'];
// or use localStorage.removeItem('favoriteflavor');

var taste = localStorage.getItem('favoriteflavor');

if(taste == null){

   console.log('favoriteflavor is null');

}
else
{
   console.log('favoriteflavor is NOT null');
}

http://jsfiddle.net/mowglisanu/AwsyE/10/

Answer 2

您将项目设置为''在此处：

localStorage.setItem('favoritefla','');

并测试输出是否为== null

if(localStorage['favoriteflavor'] == 'null'

当它等于''，因为你自己之前已经设置了这个值。

我相信您正在尝试了解浏览器是否具有localStorage容量，您可以通过测试是否可以插入和删除此对象中的项目来执行此操作，如下所示：

var hasStorage = (function() {
  try {
    localStorage.setItem(mod, mod);
    localStorage.removeItem(mod);
    return true;
  } catch(e) {
    return false;
  }
}());

如果broswer具有localStorage容量，则上述函数将返回true。我希望它有所帮助，欢呼

javascript本地存储

2 个答案: