本文介绍了在HTML5 localStorage中存储对象的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我想在HTML5 localStorage
中存储JavaScript对象,但我的对象显然正在转换为字符串。
我可以使用 localStorage
存储和检索原始JavaScript类型和数组,但对象似乎不起作用。他们应该吗?
以下是我的代码:
var testObject = {'one' :1,'two':2,'three':3};
console.log('typeof testObject:'+ typeof testObject);
console.log('testObject properties:');
for(var test in testObject){
console.log(''+ prop +':'+ testObject [prop]);
}
//将对象放入存储区
localStorage.setItem('testObject',testObject);
//从存储中检索对象
var retrievedObject = localStorage.getItem('testObject');
console.log('typeof retrieveObject:'+ typeof retrievedObject);
console.log('retrieveObject的值:'+ retrieveObject);
控制台输出是
typeof testObject:object
testObject属性:
one:1
two:2
three:3
typeof retrievedObject:string
retrieveObject的值:[object Object]
它看起来像我在存储它之前, setItem
方法将输入转换为字符串。
我在Safari,Chrome和Firefox,所以我认为这是我对规范的误解,而不是浏览器 - 特定的错误或限制。
我尝试了解。我不完全明白它的意思,但也许我的问题与我的对象的属性不能枚举(???)
是否有一个简单的解决方法?
更新:W3C最终改变了他们对结构化克隆规范的看法,并决定改变规范以匹配实现。请参阅。所以这个问题不再是100%有效的,但答案仍然可能是有趣的。
=http://developer.apple.com/safari/library/documentation/iPhone/Conceptual/SafariJSDatabaseGuide/Name-ValueStorage/Name-ValueStorage.html#//apple_ref/doc/uid/TP40007256-CH6-SW1 = noreferrer> Apple ,和文档,该功能似乎仅限于处理字符串键/值对。
解决方法可以是 stringify
在存储它之前,先对对象进行分析,然后在检索它时解析它:
var testObject = {'one':1,'two':2,'three':3};
//将对象放入存储区
localStorage.setItem('testObject',JSON.stringify(testObject));
//从存储中检索对象
var retrievedObject = localStorage.getItem('testObject');
console.log('retrieveObject:',JSON.parse(retrieveObject));
I'd like to store a JavaScript object in HTML5 localStorage
, but my object is apparently being converted to a string.
I can store and retrieve primitive JavaScript types and arrays using localStorage
, but objects don't seem to work. Should they?
Here's my code:
var testObject = { 'one': 1, 'two': 2, 'three': 3 };
console.log('typeof testObject: ' + typeof testObject);
console.log('testObject properties:');
for (var prop in testObject) {
console.log(' ' + prop + ': ' + testObject[prop]);
}
// Put the object into storage
localStorage.setItem('testObject', testObject);
// Retrieve the object from storage
var retrievedObject = localStorage.getItem('testObject');
console.log('typeof retrievedObject: ' + typeof retrievedObject);
console.log('Value of retrievedObject: ' + retrievedObject);
The console output is
typeof testObject: object
testObject properties:
one: 1
two: 2
three: 3
typeof retrievedObject: string
Value of retrievedObject: [object Object]
It looks to me like the setItem
method is converting the input to a string before storing it.
I see this behavior in Safari, Chrome, and Firefox, so I assume it's my misunderstanding of the HTML5 Web Storage spec, not a browser-specific bug or limitation.
I've tried to make sense of the structured clone algorithm described in http://www.w3.org/TR/html5/infrastructure.html. I don't fully understand what it's saying, but maybe my problem has to do with my object's properties not being enumerable (???)
Is there an easy workaround?
Update: The W3C eventually changed their minds about the structured-clone specification, and decided to change the spec to match the implementations. See https://www.w3.org/Bugs/Public/show_bug.cgi?id=12111. So this question is no longer 100% valid, but the answers still may be of interest.
解决方案
Looking at the Apple, Mozilla and Microsoft documentation, the functionality seems to be limited to handle only string key/value pairs.
A workaround can be to stringify your object before storing it, and later parse it when you retrieve it:
var testObject = { 'one': 1, 'two': 2, 'three': 3 };
// Put the object into storage
localStorage.setItem('testObject', JSON.stringify(testObject));
// Retrieve the object from storage
var retrievedObject = localStorage.getItem('testObject');
console.log('retrievedObject: ', JSON.parse(retrievedObject));
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