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javascriptfirefoxdombookmarkletuserscripts

Firefox Or JavaScript, count the DOM

I'm sure this is simple but I have no idea how to do it. How do i count the amount of DOM elements in my HTML page? I wanted to do this in a userscript or bookmarklet but i have no idea how to start!

Solution

  • Use this for Element nodes:

    document.getElementsByTagName("*").length

    For any node, you can extend Node like this:

    Node.prototype.countChildNodes = function() {
  return this.hasChildNodes()
    ? Array.prototype.slice.apply(this.childNodes).map(function(el) {
        return 1 + el.countChildNodes();
      }).reduce(function(previousValue, currentValue, index, array){
        return previousValue + currentValue;
      })
    : 0;
};

    Then all you need to do is to call document.countChildNodes.