jQuery index() in vanilla javascript

Question

As per the jQuery api, the complementary operation to .get(), which accepts an index and returns a DOM node, .index() can take a DOM node and returns an index.

Answer 1

I've modified Travis J answer to not include TextNodes and made a function out of it.

You can run it in the console and see (on stackoverflow).

Classic way:

function getNodeindex( elm ){ 
    var c = elm.parentNode.children, i = 0;
    for(; i < c.length; i++ )
        if( c[i] == elm ) return i;
}

// try it
var el = document.getElementById("sidebar");
getNodeindex(el);

With ES2015:

function getNodeindex( elm ){ 
    return [...elm.parentNode.children].findIndex(c => c == elm)
    // or
    return [...elm.parentNode.children].indexOf(elm)
}

Demo:

const getNodeindex = elm => [...elm.parentNode.children].indexOf(elm)

get index
get index
get index

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I also want to point to another thread on the same matter, which has a great answer (for people seeking older IE support)