title: How to get object length
body: <p>Is there any built-in function that can return the length of an object?</p>
  
  <p>For example, I have <code>a = { 'a':1,'b':2,'c':3 }</code> which should return <code>3</code>. If I use <code>a.length</code> it returns <code>undefined</code>.</p>
  
  <p>It could be a simple loop function, but I'd like to know if there's a built-in function?</p>
  
  <p>There is a related question (<a href="https://stackoverflow.com/questions/3241782/length-of-a-json-object">Length of a JSON object</a>) - in the chosen answer the user advises to transform object into an array, which is not pretty comfortable for my task.</p>