JavaScript modifies json file format

JSON (JavaScript Object Notation) is a lightweight data exchange format that organizes data in key-value pairs and is widely used in front-end development. In actual development, we sometimes need to modify some content or format of the JSON file. In JS, JSON modification can be achieved through some methods, and the operation is very simple.

This article will introduce how to use JavaScript to modify the JSON file format.

1. Convert JSON into objects

We need to convert the data in JSON format into JS objects before we can modify it. You can use the parse() method to convert JSON data into an object, for example:

let jsonString = '{"name": "Mandy", "age": 20}';
let jsonObj = JSON.parse(jsonString);
console.log(jsonObj);

Explain the above code, we first define a string jsonString containing JSON data, and in the second line we call JSON. The parse() method converts jsonString into an object jsonObj. Finally, we output the converted object, and the console will output the following information:

{name: "Mandy", age: 20}

2. Modify the JSON data attributes

Next, We can easily modify the properties in JSON. For example, we can modify Mandy's age in the above example:

jsonObj.age = 21;
console.log(jsonObj);

We only need to use dots or brackets to access the properties in the object, and then reassign the values. That’s it.

3. Convert the modified object into a JSON string

After we finish modifying the JSON data, we need to convert the modified object into a string format. You can use stringify( ) method, the code is as follows:

let newJsonString = JSON.stringify(jsonObj);
console.log(newJsonString);

stringify() method accepts an object as a parameter, and then converts the object into a string in JSON format. We can get the converted string by redefining the newJsonString variable.

4. Add attributes in JSON

When we need to add new attributes to the JSON file, it is easy to add new attributes directly using dots or square brackets, for example:

jsonObj.gender = 'female';
console.log(jsonObj);

This code will add a Gender attribute in JSON with the attribute value female.

5. Delete JSON data attributes

We can use the delete operator to delete attributes in JSON, for example:

delete jsonObj.age;
console.log(jsonObj);

This code will delete the age attribute in the jsonObj object , we can see from the output that the age attribute has been deleted.

6. Modify JSON array data

In addition to objects, JSON can also contain arrays. Let's take a look at how to modify a JSON array.

First, we need to convert the string of the JSON array into a JS object, for example:

let jsonArrString = '[{"name": "Jack", "age": 25}, {"name": "Lucy", "age": 27}]';
let jsonArray = JSON.parse(jsonArrString);
console.log(jsonArray);

In this code, we define a string jsonArrString containing a JSON array, using parse () method to convert it to an object type, and the final result will be output:

[{name: "Jack", age: 25}, {name: "Lucy", age: 27}]

Next we can modify the data according to the subscript of the object, for example:

jsonArray[0].age = 26;
console.log(jsonArray);

This code Modify the age property in the first object to 26. Of course, you can also use the push() method to add an object to the JSON array. The code is as follows:

jsonArray.push({"name":"Alex","age":30});
console.log(jsonArray);

This code will add an object containing the name and age attributes to the JSON array.

7. Summary

Through the above introduction, we can find that it is very convenient to use JavaScript to modify the JSON file format. It should be noted that we need to convert the JSON string into an object before modifying it. The modified object also needs to be converted into string format through the stringify() method.

In short, for front-end developers, it is very necessary to be familiar with the operation of JSON. It allows us to better manage and maintain data, and it will also play a big role in actual development.

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