replace function

HTML

<h3>Here is my string, I want to make changes here! hoot! <span style="color: #4a1e51;">and here but not within the span tag</span></h3>

JavaScript

var data = ' data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEBLAEsAAD/2wBDAAYEBQYFBAYGBQYHBwYI…caOUMGSI2j2SD3HmtHskMkwAeyRL2LjAa2xwoiL3HjbX6Qog0STGzb+kJCGJY28fCExM//2Q==';
//var test =/^data:image\/jpeg;base64,/;
var test =/^data/;
//var first = /^data:;
//var middle = /image\/jpeg;
//var last= /;base64,/;

var testin = data.replace(test ,'OUI');
//console.log(first);
//console.log(middle);
var re = /pommes/;
var str = "Les pommes sont rondes. Les pommes sont juteuses.";
var nouvelleStr = str.replace(re, "");
console.log(testin);