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

Answer 1

using slice, apply and join method.

var print = Array.prototype.slice.apply( obj );
alert('length='+print.length+' list'+print.join());

Answer 2

Recursive solution for browsers that support ECMAScript 5:

var getObjectKeys = function(obj) {
    var keys = Object.keys(obj);
    var length = keys.length;

    if (length !== 0) {
        for (var i = 0; i < length; i++) {
            if (typeof obj[keys[i]] === 'object') {
                keys[keys[i]] = getObjectKeys(obj[keys[i]]);
            }
        }
    }

    return keys;
};

Answer 3

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

console.log(Object.keys(obj));
console.log(Object.keys(obj).length)

Answer 4

If you decide to use Underscore.js you better do

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

var keys = [];
_.each( obj, function( val, key ) {
    keys.push(key);
});
console.log(keys.lenth, keys);

Answer 5

In JavaScript, an object is a standalone entity, with properties and type.

For fetching values from Object in form of array: Object.values(obj) // obj is object name that you used Result -> ["value1", "value2", "value3", "value4"]

For fetching keys from Object in form of array: Object.keys(obj) // obj is object name that you used Result -> ["key1", "key2", "key3", "key4"]

As both functions are returning array you can get the length of keys or value by using length property. For instance - Object.values(obj).length or Object.keys(obj).length

Answer 6

obj = {'a':'c','b':'d'}

You can try:

[index for (index in obj)] 

this will return:

['a','b']

to get the list of keys or

[obj[index] for (index in obj)]

to get the values