How To Detect Htmlcollection/nodelist In Javascript?

I'm not sure my current implementation is available all the time: function isNodeList(nodes) { var result = Object.prototype.toString.call(nodes); // modern browser such as

Solution 1:

The following should return true, if nodes is of type NodeList

NodeList.prototype.isPrototypeOf(nodes)

@DavidSpector, for HTMLCollection you can similarly use :

HTMLCollection.prototype.isPrototypeOf(collection)

Solution 2:

I would structure the code differently:

functionisNodeList(nodes) {
    var stringRepr = Object.prototype.toString.call(nodes);

    returntypeof nodes === 'object' &&
        /^\[object (HTMLCollection|NodeList|Object)\]$/.test(stringRepr) &&
        (typeof nodes.length === 'number') &&
        (nodes.length === 0 || (typeof nodes[0] === "object" && nodes[0].nodeType > 0));
}

Notes:

• less return paths make easier-to-read code
• stick with one type of logic, if possible (i.e. use less negated checks)
• "item" is not mandatorily in a nodeList
• use hasOwnProperty() instead of in
• use square brackets to index into the list
• I don't think a try/catch is really necessary, but that might be wrong - you decide
• check for nodeType instead of tagName, as text nodes or comments do not have a name
• add more checks to the && chain if you see fit

Solution 3:

script:

Element.prototype.isNodeList = function() {returnfalse;}
NodeList.prototype.isNodeList = HTMLCollection.prototype.isNodeList = function(){returntrue;}

use like this:

var d; // HTMLCollection|NodeList|Elementif(d.isNodeList()){
  /*
    it is HTMLCollection or NodeList
    write your code here
  */
}else{
  /*
    it is not HTMLCollection and NodeList
    write your code here
  */
}

Solution 4:

Here is how to test if an object is a NodeList in modern browsers:

if (nodes instanceof NodeList) {
  // It's a NodeList object
}

Solution 5:

Check if variable is an HTMLcollection or a dom element

var foo = document.getElementById('mydiv');
  var foo2 = document.getElementsByClassName('divCollection');
  console.log(foo instanceofHTMLElement);
  console.log(foo instanceofHTMLCollection);