やっつけです。画面左上に入力ボックスが出ます。ブックマークレットにすると良いかもです。
(function(){ function $id(){ var elem, id; switch(arguments.length){ case 1: elem = document ; id = arguments[0]; break; case 2: elem = arguments[0]; id = arguments[1]; break; default: throw "argument error"; } return elem.getElementById(id); } function createElement(parent, tagName, attributes, styles, innerHTML){ var e = document.createElement(tagName); if(attributes){ for(var key in attributes){ e.setAttribute( key, attributes[key] ); }} if(styles){ for(var key in styles){ e.style[key] = styles[key]; }} if(innerHTML){ e.innerHTML = innerHTML; } if(parent){ parent.appendChild(e); } return e; } var box = createElement( document.body , "form" , null , { position: "fixed" , left: 0 , top: 0 , background: "#ddd" , padding: "4px" , border: "solid 1px black" } , null ); var inputMatch = createElement(box, "input", { id: "match" }, { display: "block" }, null ); inputMatch.focus(); var inputReplace = createElement(box, "input", { id: "replace" }, { display: "block" }, null); var button = createElement( box , "input" , { type: "submit", value: "replace" } , null , null ); button.addEventListener( "click" , function(e){ traverse(document , $id("match").value , $id("replace").value); e.preventDefault(); } , false ); var buttonDelete = createElement( box , "input" , { type: "button", value: "x" } , null, null ); buttonDelete.addEventListener( "click" , function(){ document.body.removeChild( box ); } , false ); function traverse(elem, matchString, replaceString){ var kids = elem.childNodes; var kid; for(var a=0; a<kids.length; a++){ kid = kids.item(a); if(kid.nodeType == 3){ kid.nodeValue = kid.nodeValue .replace(matchString, replaceString); }else{ if(kid.childNodes.length>0){ traverse(kid, matchString, replaceString); } } } } })();