How to get all attributes of DOM element? [duplicate]

Question

How to copy all user defined attributes for a DOM element into an array? I Unsuccessfully tested to get ["type", "onClick",'value','id'] See the following code

Js

 var obj=document.getElementById('input')/*.attributes*/,
     array=[],
     index=0;
     for(array[index++] in obj);
 console.log(array);

html

<input type='button' onClick="Start()" id='input' value="Start"/>

Answer 1

Get all Attributes from a HTML element with Javascript/jQuery

Using it with your JS, you get:

var obj=document.getElementById('input')/*.attributes*/,
     arr=[],
     index=0;

for (var i = 0, atts = obj.attributes, n = atts.length; i < n; i++){
    arr.push(atts[i].nodeName);
}
 console.log(arr);

Answer 2

The attributes are available on the attributes NamedNodeMap; you access each one with [] notation, and there's a length.

So:

var array = Array.prototype.map.call(
    document.getElementById('input').attributes,
    function(attr) {
        // Use nodeName for the name, nodeValue for the value
        return attr.nodeName;
    });
snippet.log(array.join(", "));

<input type='button' onClick="Start()" id='input' value="Start"/>
<!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="https://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>