Replace text in a website

Question

I'm looking to replace text in a webpage (any webpage I want to run it on) using JavaScript. I'm not an expert in JavaScript, so I am sort of lost. If I can help it I would like to avoid jQuery.

Through Google, I've found this stackoverflow question. But when I inject document.body.innerHTML = document.body.innerHTML.replace('hello', 'hi'); into a webpage it sort of messes the page up. It seems to make the page revert to basic text and formatting.

Also, I'm wondering if the regex code from here, could be used. Again, I really am not sure how to use it. What it would do is replace only webpage text - not links or filenames.

I'm using Google Chrome incase that matters.

Answer 1

You could perform your repleacements on all the just the text nodes in the DOM:

function replaceTextOnPage(from, to){
  getAllTextNodes().forEach(function(node){
    node.nodeValue = node.nodeValue.replace(new RegExp(quote(from), 'g'), to);
  });

  function getAllTextNodes(){
    var result = [];

    (function scanSubTree(node){
      if(node.childNodes.length) 
        for(var i = 0; i < node.childNodes.length; i++) 
          scanSubTree(node.childNodes[i]);
      else if(node.nodeType == Node.TEXT_NODE) 
        result.push(node);
    })(document);

    return result;
  }

  function quote(str){
    return (str+'').replace(/([.?*+^$[\]\\(){}|-])/g, "\\$1");
  }
}

Quote function borrowed from this answer.

Usage:

replaceTextOnPage('hello', 'hi');

Note that you will need to SHIM forEach in older browsers or replace that code with a loop like so:

var nodes = getAllTextNodes();
for(var i = 0; i < nodes.length; i++){
    nodes[i].nodeValue = nodes[i].nodeValue.replace(new RegExp(quote(from), 'g'), to);
}