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javascript tutorial (w3schools)

Snippety

  1. Ajax (w3schools)
    var req = new XMLHttpRequest();
    // the request must be in the same domain as the containing webpage
    req.open("GET", "/cgi-bin/test.cgi", false);
    req.send();
    document.write(req.responseText);
  2. download file (workaround for "save to a local file")
    var s = "text";
    var blob = new Blob([s]);
    var o = URL.createObjectURL(blob);
    var e = document.createElement("a");
    e.href = o;
    e.innerHTML = "link";
    e.download = "save_as_filename.txt";
    document.body.appendChild(e);
    // creates a new link at the bottom of the page, that can be saved locally
  3. enumerate NodeList
    var aElem = document.getElementsByTagName("input");
    Array.prototype.forEach.call(aElem, function(e) {
      console.log(e.name);
    });
  4. events
    var inp = document.body.getElementsByTagName("input").item(3);
    inp.onkeydown = null
    inp.onkeypress = null;
    document.onkeypress = function (e) {
      console.log(String.fromCharCode(e.charCode) + '=' + e.charCode);
    // getting int from str, i.g. parseInt("a0", 16)
    // to get char code: str.charCodeAt() return false; };
    elem.addEventListener("click", function(){
    alert("event");
    }); aa
  5. logging
    console.log('something');
  6. modifying document
      span = document.getElementById('dataMod');
    if (span != null) {
    data = dataMod.textContent.substring(8, 18);
    span.textContent = data.substring(8, 10) + '.' + data.substring(5, 7)
    + '.' + data.substring(0, 4);
    }
  7. style, toggleVisibility
    <button onclick='toggleVisibility()'>Rozwiązanie</button>
    <div id="sol"> <script> var bVisible = true; function toggleVisibility() { bVisible = !bVisible; sVisible = bVisible ? "initial" : "hidden"; // "visible" document.getElementById('sol').style.visibility = sVisible; } toggleVisibility(); </script> b</div>
  8. timeout
      window.setTimeout(fun, 1000); /* possible args after timeout in ms */

    // cancel all timeouts http://stackoverflow.com/a/8860203/772981
    var id = window.setTimeout(function() {}, 0);
    while (id--) {
    window.clearTimeout(id); // will do nothing if no timeout with id is present
    }