Getting JavaScript object key list

Question

I have a JavaScript object like

var obj = {    key1: 'value1',    key2: 'value2',    key3: 'value3',    key4: 'value4' } 

How can I get the length and list of keys in this object?

Answer 1

var obj = {     key1: 'value1',     key2: 'value2',     key3: 'value3',     key4: 'value4'  }  var keys = Object.keys(obj);  console.log('obj contains ' + keys.length + ' keys: '+  keys);

It's supported on most major browsers now.

Answer 2

var obj = {   key1: 'value1',   key2: 'value2',   key3: 'value3',   key4: 'value4' }; var keys = [];  for (var k in obj) keys.push(k);  console.log("total " + keys.length + " keys: " + keys);