insertdeletetext.js

/*
<p>But haven't the sweetest idea <button>DELETE</button></p>
<p>To me buzz is <button>INSERT</button></p>

We'll use the two methods to do two simple things with this HTML: (1) Remove the word "idea" and (2) insert the word "onomatopoeia". Here's the JavaScript:
*/

var pars = document.querySelectorAll('p'),
    btns = document.querySelectorAll('button'),
    text;

btns[0].addEventListener('click', function () {
  text = pars[0].firstChild;
  text.deleteData(25, 4);
}, false);

btns[1].addEventListener('click', function () {
  text = pars[1].firstChild;
  text.insertData(14, 'onomatopoeia ');
}, false);