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How to flatten a JavaScript object into a single-depth object?

PHPzforward: 2023-08-24 10:29:071347browse

如何将 JavaScript 对象压平为单深度对象？

In JavaScript, objects can be created using curly braces {}. This is called an object literal. Object literals can contain properties and methods.

What is flattening?

Flattening is the process of reducing an object to a single depth object. In other words, all properties and methods of the object are contained in a single depth object.

How to flatten an object?

There are multiple ways to flatten an object.

Use for...in loop

The for...in loop can be used to iterate over the properties of an object. For each property we can add it to a new object.

The following is a code snippet that uses a for...in loop to flatten an object.

<!doctype html>
<html>
<head>
   <title>Example - flatten an object</title>
</head>
<body>
   <div id="result1">Original Object: </div>
   <div id="result2">Flatten Object: </div>
   <script>
      var obj = {
         "a": 1,
         "b": 2,
         "c": {
            "d": 3,
            "e": 4
         }
      };
      var newObj = {};
      for (var key in obj) {
         if (typeof obj[key] === "object") {
            for (var subKey in obj[key]) {
               newObj[subKey] = obj[key][subKey];
            }
         } else {
            newObj[key] = obj[key];
         }
      }
      document.getElementById("result1").innerHTML += JSON.stringify(obj)
      document.getElementById("result2").innerHTML += JSON.stringify(newObj)
      console.log(newObj);   </script>
</body>
</html>

In the above code, we declare an object literal named obj. Then we declare an empty object literal named newObj. We use a for...in loop to iterate over the properties of obj. For each attribute, we check whether the attribute value is an object. If the property value is an object, then we again use a for...in loop to iterate over the child properties of the property value.

For each subproperty, we add it to the newObj object with the subproperty name as the key. If the property value is not an object, then we add the property to the newObj object using the property name as the key. Finally, we log newObj to the console.

Benefits of flattening

Flattening objects has multiple benefits. Some of them are-

Ease of Access Properties

When an object is flattened, all properties and methods are included in an object. This makes accessing properties and methods easy.

Easy to manipulate data

When an object is flattened, the data is contained within a single object. This makes it easy to manipulate the data.

Easy to serialize

When an object is flattened, it can be easily serialized. Serialization is the process of converting objects into a format that can be stored or transmitted.

Disadvantages of flattening

Flattening objects has some disadvantages. Some of them are-

Data redundancy

When an object is flattened, data redundancy may occur. Data redundancy means the same data is stored in multiple places.

Maintenance difficulties

When an object is flattened, it can be difficult to maintain. This is because all properties and methods are contained within an object.

in conclusion

In short, flattening is the process of reducing an object to a single-depth object. There are several ways to flatten an object. Some of the benefits of flattening objects are ease of accessing properties, ease of manipulating data, and ease of serialization. Flat objects have shortcomings such as data redundancy and difficulty in maintenance.

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