javascript baocun error report

JavaScript front-end development is a very popular field at present. In this field, data processing and data storage are very important parts. In the process of data storage, various error problems often occur, among which The most common one is the error that occurs when JavaScript stores data. Let's analyze the errors and solutions that occur when JavaScript stores data.

1. Common JavaScript storage data errors

1. When using localStorage for data storage, if we store an object directly in it instead of converting it into a JSON string and then storing it, An error will appear, and the error message is: Data clone failed because the item being stored has a property that cannot be cloned.
2. When using sessionStorage for data storage, if we store a cyclic reference object directly, an error will also appear. The error message is: Data cyclic structure cannot be persisted in storage.

2. Solution

1. Convert the object into a JSON string and then store it. The JSON.stringify() method can convert objects into JSON strings, and the JSON.parse() method can convert JSON strings into objects.
2. Solve the circular reference problem. Circular reference refers to a situation where objects refer to each other, forming a closed loop. When dealing with circular references, we can use a circular reference detection library. For example, the fast-json-patch library provides the function of circular reference detection.

3. Example Analysis

Let’s use some examples to illustrate the errors and solutions that occur when JavaScript stores data.

1. Error message

When we use localStorage to store an object, if we do not convert it into a JSON string before storing it, the following error message will appear:

Data clone failed because the item being stored has a property that cannot be cloned.

2. Solution

Convert the object into a JSON string and then store it That's it:

let obj = {name: 'Tom', age: 18};
// Convert the object into a JSON string
let str = JSON.stringify(obj);
// Store JSON string
localStorage.setItem('user', str);

3. Error message

When we use sessionStorage to store a circular reference object, the following error message will appear:

Data cyclic structure cannot be persisted in storage.

4. Solution

Resolve circular reference To solve the problem, you can use the circular reference detection function provided by the fast-json-patch library. The code is as follows:

const jsonPatch = require('fast-json-patch')
const obj = { name: 'Tom ', friends: [] }
obj.friends.push(obj)

const valid = jsonPatch.validate(obj)
if (valid === undefined) {
console. log('The object is valid')
sessionStorage.setItem('user', JSON.stringify(obj))
} else {
console.log('There is a circular reference to the object')
}

Summary

It is a very common problem for JavaScript to get errors when storing data. These error messages remind us of some limitations and errors that occur when we store data, and we need to do some special things when storing data. processing. For example, we need to use the JSON.stringify() method to convert the object into a JSON string before storing it, and we also need to use a circular reference detection library to solve the circular reference problem. Only through learning and practice can we better master the knowledge and skills related to JavaScript data storage.

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