[html] making a paragraph in html contain a text from a file

I have an html paragraph (inside a div) in which I want to display a simple fixed text. The text is a bit long so I'd rather the text will be in a seperate txt file.
something like

<div><p txt=file.txt></p></div>

Can I do something like that?

You can use a simple HTML element <embed src="file.txt"> it loads the external resource and displays it on the screen no js needed

Javascript will do the trick here.

function load() {
    var file = new XMLHttpRequest();
    file.open("GET", "http://remote.tld/random.txt", true);
    file.onreadystatechange = function() {
      if (file.readyState === 4) {  // Makes sure the document is ready to parse
        if (file.status === 200) {  // Makes sure it's found the file
          text = file.responseText;
          document.getElementById("div1").innerHTML = text;
        }
      }
    }
}

window.onLoad = load();

Here is a javascript code I have tested successfully :

    var txtFile = new XMLHttpRequest();
    var allText = "file not found";
    txtFile.onreadystatechange = function () {
        if (txtFile.readyState === XMLHttpRequest.DONE && txtFile.status == 200) {
            allText = txtFile.responseText;
            allText = allText.split("\n").join("<br>");
        }

        document.getElementById('txt').innerHTML = allText;
    }
    txtFile.open("GET", '/result/client.txt', true);
    txtFile.send(null);

I would use javascript for this.

var txtFile = new XMLHttpRequest();
txtFile.open("GET", "http://my.remote.url/myremotefile.txt", true);
txtFile.onreadystatechange = function() {
  if (txtFile.readyState === 4 && txtFile.status == 200) {
     allText = txtFile.responseText;
  }
document.getElementById('your div id').innerHTML = allText;

This is just a code sample, would need tweaking for all browsers, etc.

You can do something like that in pure html using an <object> tag:
<div><object data="file.txt"></object></div>

This method has some limitations though, like, it won't fit size of the block to the content - you have to specify width and height manually. And styles won't be applied to the text.