How to implement "prevUntil" in Vanilla JavaScript without libraries?

Example Using previousElementSibling:

    var className = "needle";
    var element = clickedElement;
    while(element.previousElementSibling && element.previousElementSibling.className != className) {
       element = element.previousElementSibling;
    }
    element.previousElementSibling; // the element or null

Use .children in combination with .parentNode. Then filter the NodeList, after converting it into an array: http://jsfiddle.net/pimvdb/DYSAm/.

var div = document.getElementsByTagName('div')[0];
var siblings = [].slice.call(div.parentNode.children) // convert to array
                 .filter(function(v) { return v !== div }); // remove element itself
console.log(siblings);

How about this:

while ( node = node.previousElementSibling ) {
    if ( ( ' ' + node.className + ' ' ).indexOf( 'foo' ) !== -1 ) {
        // found; do your thing
        break;
    }
}

Don't bother telling me that this doesn't work in IE8...

This answer was previously published here in response to a similar question .

There are a few ways to do it.

Either one of the following should do the trick.

// METHOD A (ARRAY.FILTER, STRING.INDEXOF)
var siblings = function(node, children) {
    siblingList = children.filter(function(val) {
        return [node].indexOf(val) != -1;
    });
    return siblingList;
}

// METHOD B (FOR LOOP, IF STATEMENT, ARRAY.PUSH)
var siblings = function(node, children) {
    var siblingList = [];
    for (var n = children.length - 1; n >= 0; n--) {
        if (children[n] != node) {
            siblingList.push(children[n]);
        }  
    }
    return siblingList;
}

// METHOD C (STRING.INDEXOF, ARRAY.SPLICE)
var siblings = function(node, children) {
   siblingList = children;
   index = siblingList.indexOf(node);
   if(index != -1) {
       siblingList.splice(index, 1);
   }
   return siblingList;
}

FYI: The jQuery code-base is a great resource for observing Grade A Javascript.

Here is an excellent tool that reveals the jQuery code-base in a very streamlined way. http://james.padolsey.com/jquery/