How to expand objects using key paths in JavaScript?-JS Tutorial-php.cn

How to expand objects using key paths in JavaScript?

王林

Release： 2023-08-29 15:09:03

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如何使用 JavaScript 中的键路径展开对象？

In JavaScript, you can "flatten" an object by creating a shallow copy of it. This is useful for creating a snapshot of an object, but can cause problems if the object is modified later. If you need to unflatten an object, you can use the path of the key to restore the original structure.

Use key path

When the object is flattened, the keys are concatenated into a single string. You can use this string to expand objects by creating objects with the same keys and values.

For example, consider the following object.

var obj = { 
   "foo.bar": "baz", 
   "foo.qux": "quux" 
};

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You can expand an object by creating an object with the same keys and values.

<!doctype html>
<html>
<head>
   <title>Examples</title>
</head>
<body>
   <div id="result1">Original Object:</div><br/>
   <div id="result2">After Unflatten:</div>
   <script>
      var obj = {
         "foo.bar": "baz",
         "foo.qux": "quux"
      };
      var unflattenedObj = {};
      for (var key in obj) {
         var value = obj[key];
         var path = key.split(".");
         var current = unflattenedObj;
         for (var i = 0; i < path.length - 1; i++) {
            var part = path[i];
            current[part] = current[part] || {};
            current = current[part];
         }
         current[path[path.length - 1]] = value;
      }
      document.getElementById("result1").innerHTML += JSON.stringify(obj);
      document.getElementById("result2").innerHTML += JSON.stringify(unflattenedObj);
      console.log(unflattenedObj)
   </script>
</body>
</html>

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Benefits of canceling flattening

Unflattening an object can be useful for a number of reasons. First, it helps you avoid duplicate keys. If there are two keys with the same name, they will be overwritten when the object is flattened. Secondly, it helps you preserve the original structure of the object. This can be important when you need to pass an object to a function that requires a certain format.

in conclusion

Unflattening an object is simple, just create an object with the same keys and values. This is useful to avoid duplicate keys and preserve the original object structure.

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