How Can I Efficiently Retrieve Object Property Names in JavaScript?

Retrieving Object Properties in JavaScript

Determining the properties of a JavaScript object can be crucial for various programming tasks. To achieve this, we'll explore efficient methods for extracting a list of property names from an object.

Object.keys Method

For modern browsers and environments (IE9 , FF4 , Chrome5 , Opera12 , Safari5 ), the built-in Object.keys() method provides a straightforward solution:

var myObject = { ircEvent: "PRIVMSG", method: "newURI", regex: "^http://.*" };
var keys = Object.keys(myObject);

console.log(keys);
// Output: ["ircEvent", "method", "regex"]

Polyfill for Object.keys

If support for older browsers is required, an implementation can be polyfilled:

var getKeys = function(obj) {
   var keys = [];
   for (var key in obj) {
      keys.push(key);
   }
   return keys;
}

Extension of Object.prototype

Alternatively, one can extend the Object.prototype to include a keys() method:

Object.prototype.keys = function() {
   var keys = [];
   for (var key in this) {
      keys.push(key);
   }
   return keys;
}

var keys = myObject.keys();

This approach has potential side effects and should be used with caution.

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