Javascript read html from url into string

Your answer is Ajax. It can POST and GET data from an URL, just like browsing a website, and it will return the HTML as a string.

If you plan on using jQuery (real handy), it is easy to use Ajax. Like this example (does not work without the library):

$.ajax({
    url : "/mysite/file.html",
    success : function(result){
        alert(result);
    }
});

If you want to use default Javascript, take a look at http://www.w3schools.com/ajax/default.asp

var xmlhttp;
if (window.XMLHttpRequest) { // code for IE7+, Firefox, Chrome, Opera, Safari
    xmlhttp = new XMLHttpRequest();
}
else { // code for IE6, IE5
    xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function() {
    if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
        document.getElementById("myDiv").innerHTML = xmlhttp.responseText;
    }
}
xmlhttp.open("GET", "ajax_info.txt", true);
xmlhttp.send();

Modern Promise-based Fetch API solution (no more XMLHttpRequest or jQuery.ajax()):

fetch('data.txt')
  .then(response => response.text())
  .then(data => console.log(data));

Example using async/await:

async function myFetch() {
  let response = await fetch('data.txt');

  if (!response.ok) {
    throw new Error(`HTTP error! status: ${response.status}`);
  }

  let text = await response.text(); // await ensures variable has fulfilled Promise
  console.log(text);
}

There's not much to add to what Niels and rich.okelly have said. AJAX is your way to go.

Keep in mind though, that cross-domain restrictions will prohibit you to access data that is not in the same domain. You'll find a possible workaround here.

IN Javascript to get data without using alert() :

    $.ajax({
    url : "/mysite/file.html",
    async:false,            //this is the trick
    success : function(result){
                 //does any action
               } 
    });