如何在用户离线时将 xml 文件保存到本地存储并更新值？

Question

I am trying to code a currency converter. I am downloading the xml file from a url where the currencies and the rates are stored there. I want to save currencies to local storage so when the user is offline he will still be able to do conversion. I print the xml file in the console just to check if I am getting the xml file. So my question is, how do i store the currencies and the rates to local storage, and how do i update the values when the user again online? javascript:

function display(e ) {
    if ((e.target !== e.currentTarget) && e.target.id !== "clear" && e.target.id !== "kati") {
        var clickedItem = e.target.id;
        document.getElementById("display").value =  document.getElementById("display").value + clickedItem;
    }
    else  if (e.target.id = "clear" && e.target.id !== "kati") {
        document.getElementById("display").value = null;
    } else if (e.target.id = "kati") {
        var ourRequest = new XMLHttpRequest();
        ourRequest.open('GET', 'https://devweb2018.cis.strath.ac.uk/~aes02112/ecbxml.php');
        ourRequest.onreadystatechange = function () {
            var data = ourRequest.responseText;
            console.log(data);
        };
        ourRequest.send();
    }
    e.stopPropagation();
}

The url for the xml file is displayed in the code.

Answer 1

Yes, as Chris has already said, you can use default localStorage:

localStorage.setItem("hello","world");
localStorage.getItem("hello"); //world

For example, after you've got response

ourRequest.onreadystatechange = function () {
 if (ourRequest.readyState === 4) {
  if (xhr.status == 200){
   if (ourRequest.status == 200){
     var data = ourRequest.responseXML;
     var someTag = data.getElementsByTagName("someTag");
     //something like this
     localStorage.setItem("someTagValue",someTag[0].childNodes[0].nodeValue);
   }
  }    
};