如何高效地计算JavaScript中的对象的键/属性的数量？ [英] How to efficiently count the number of keys/properties of an object in JavaScript?

问题描述

计算对象的键/属性数量的最快方法是什么？它有可能做到这一点，而不迭代的对象？即不做

What's the fastest way to count the number of keys/properties of an object? It it possible to do this without iterating over the object? i.e. without doing

var count = 0;
for (k in myobj) if (myobj.hasOwnProperty(k)) count++;

（Firefox提供了一个神奇的 __ count __ 属性，

(Firefox did provide a magic __count__ property, but this was removed somewhere around version 4.)

推荐答案

要在任何ES5兼容的环境中执行此操作，例如节点，Chrome，IE 9+，FF 4+或Safari 5 +：

To do this in any ES5-compatible environment, such as Node, Chrome, IE 9+, FF 4+, or Safari 5+:

Object.keys(obj).length

• 浏览器兼容性


• Object.keys文档
  
  
  
  • （包括您可以添加到非ECMA5浏览器的方法）
  
  

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