How to get the pure text without HTML element using JavaScript?

I have the 1 button and some text in my HTML like the following:

function get_content(){
   // I don't know how to do in here!!!
}

<input type="button" onclick="get_content()" value="Get Content"/>
<p id='txt'>
<span class="A">I am</span>
<span class="B">working in </span>
<span class="C">ABC company.</span>
</p>

When the user clicks the button, the content in the <p id='txt'> will become the follow expected result:

<p id='txt'>
// All the HTML element within the <p> will be disappear
I am working in ABC company.
</p>

Can anyone help me how to write the JavaScript function?

Thank you.

You can use this:

var element = document.getElementById('txt');
var text = element.innerText || element.textContent;
element.innerHTML = text;

Depending on what you need, you can use either element.innerText or element.textContent. They differ in many ways. innerText tries to approximate what would happen if you would select what you see (rendered html) and copy it to the clipboard, while textContent sort of just strips the html tags and gives you what's left.

innerText also has compatability with old IE browsers (came from there).

[2017-07-25] since this continues to be the accepted answer, despite being a very hacky solution, I'm incorporating https://stackoverflow.com/users/376873/gabi-purcaru">Gabi</a>'s code into it, leaving my own to serve as a bad example.

// my hacky approach:
function get_content() {
  var html = document.getElementById("txt").innerHTML;
  document.getElementById("txt").innerHTML = html.replace(/<[^>]*>/g, "");
}
// Gabi's elegant approach, but eliminating one unnecessary line of code:
function gabi_content() {
  var element = document.getElementById('txt');
  element.innerHTML = element.innerText || element.textContent;
}
// and exploiting the fact that IDs pollute the window namespace:
function txt_content() {
  txt.innerHTML = txt.innerText || txt.textContent;
}

.A {
  background: blue;
}

.B {
  font-style: italic;
}

.C {
  font-weight: bold;
}

<input type="button" onclick="get_content()" value="Get Content (bad)" />
<input type="button" onclick="gabi_content()" value="Get Content (good)" />
<input type="button" onclick="txt_content()" value="Get Content (shortest)" />
<p id='txt'>
  <span class="A">I am</span>
  <span class="B">working in </span>
  <span class="C">ABC company.</span>
</p>

If you can use jquery then its simple

$("#txt").text()

This answer will work to get just the text for any HTML element.

This first parameter "node" is the element to get the text from. The second parameter is optional and if true will add a space between the text within elements if no space would otherwise exist there.

function getTextFromNode(node, addSpaces) {
	var i, result, text, child;
	result = '';
	for (i = 0; i < node.childNodes.length; i++) {
		child = node.childNodes[i];
		text = null;
		if (child.nodeType === 1) {
			text = getTextFromNode(child, addSpaces);
		} else if (child.nodeType === 3) {
			text = child.nodeValue;
		}
		if (text) {
			if (addSpaces && /\S$/.test(result) && /^\S/.test(text)) text = ' ' + text;
			result += text;
		}
	}
	return result;
}

Depending on what you need, you can use either element.innerText or element.textContent. They differ in many ways. innerText tries to approximate what would happen if you would select what you see (rendered html) and copy it to the clipboard, while textContent sort of just strips the html tags and gives you what's left.

innerText is not just used for IE anymore, and it is supported in all major browsers. Of course, unlike textContent, it has compatability with old IE browsers (since they came up with it).

Complete example (from Gabi's answer):

var element = document.getElementById('txt');
var text = element.innerText || element.textContent; // or element.textContent || element.innerText
element.innerHTML = text;

This works for me compiled based on what was said here with a more modern standard. This works best for multiple looks up.

let element = document.querySelectorAll('.myClass')
  element.forEach(item => {
    console.log(item.innerHTML = item.innerText || item.textContent)
  })

That should work:

function get_content(){
   var p = document.getElementById("txt");
   var spans = p.getElementsByTagName("span");
   var text = '';
   for (var i = 0; i < spans.length; i++){
       text += spans[i].innerHTML;
   }
    
   p.innerHTML = text;
}

Try this fiddle: http://jsfiddle.net/7gnyc/2/

function get_content(){
 var returnInnerHTML = document.getElementById('A').innerHTML + document.getElementById('B').innerHTML + document.getElementById('A').innerHTML;
 document.getElementById('txt').innerHTML = returnInnerHTML;
}

That should do it.

Try (short version of Gabi answer idea)

function get_content() {
   txt.innerHTML = txt.textContent;
}

function get_content() {
   txt.innerHTML = txt.textContent ;
}

span { background: #fbb}

<input type="button" onclick="get_content()" value="Get Content"/>
<p id='txt'>
<span class="A">I am</span>
<span class="B">working in </span>
<span class="C">ABC company.</span>
</p>

You want to change the I am working in ABC company. to I am working in ABC company.. These are the same strings, so I don't see a reason to, but you can accomplish this by using the JavaScript innerHTML or textContent.

element.innerHTML is a property that defines the HTML inside an element. If you type element.innerHTML = "<strong>This is bold</strong>, it'll make the text "This is bold" bold text.

element.textContent, on the other hand, sets the text in an element. If you use element.textContent = "<strong>This is bold</strong>, The text "This is bold" will not be bold. The user will literally see the text "This is bold

In your case, you can use either one. I'll use .textContent. The code to change the <p> element is below.

function get_content(){
   document.getElementById("txt").textContent = "I am working in ABC company.";
}

<input type="button" onclick="get_content()" value="Get Content"/>
<p id='txt'>
<span class="A">I am</span>
<span class="B">working in </span>
<span class="C">ABC company.</span>
</p>

This, unfortunately, will not change it because it'll change it to the same exact text. You can chance that by changing the string "I am working in ABC company." to something else.