Javascript change certain words on web pages

I'm trying to grab all the nodes in the DOM and if its text, change the value of certain words to something else. The code is not doing anything and I don't understand why. Please help.

 var elements=document.getElementsByTagName('*');

 for(var i=0;i<elements.length;i++){

var element=elements[i];

for(var j=0;j<element.childNodes.length;j++){

    var node=element.childNodes[j];
    if(node.nodeType==3){
        var text=node.nodeValue;
        var replacedText=text.replace(/jacob/g, 'toolshed')
        if(replacedText!=text){
            console.log('replaced');
            element.replaceChild(document.createTextNode(replacedText),node);
            //node.nodeValue=replacedText;
        }

      }

    }

 }